meta-nuvoton: Cleanup for Yocto override syntax change

Cleanup with
```
convert-overrides.py meta-google
```

Left over `_`.
```
$ git grep "_[a-z0-9_/-]*[ :]" -- meta-nuvoton
meta-nuvoton/conf/layer.conf:BBFILE_PATTERN_nuvoton-layer = ""
meta-nuvoton/conf/layer.conf:LAYERVERSION_nuvoton-layer = "1"
meta-nuvoton/conf/layer.conf:LAYERSERIES_COMPAT_nuvoton-layer = "gatesgarth hardknott"
meta-nuvoton/conf/machine/include/nuvoton.inc:PREFERRED_PROVIDER_virtual/kernel ?= "linux-nuvoton"
meta-nuvoton/conf/machine/include/nuvoton.inc:PREFERRED_PROVIDER_virtual/bootloader ?= "u-boot-nuvoton"
meta-nuvoton/conf/machine/include/nuvoton.inc:PREFERRED_PROVIDER_u-boot ?= "u-boot-nuvoton"
meta-nuvoton/conf/machine/include/nuvoton.inc:PREFERRED_PROVIDER_u-boot-fw-utils ?= "u-boot-fw-utils-nuvoton"
meta-nuvoton/recipes-bsp/images/npcm7xx-bingo-native_git.bb:do_install () {
meta-nuvoton/recipes-bsp/images/npcm7xx-bootblock_10.10.17.bb:do_deploy () {
meta-nuvoton/recipes-bsp/images/npcm7xx-bootblock_10.10.17.bb:addtask deploy before do_build after do_compile
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb:SUMMARY = "U-Boot bootloader fw_printenv/setenv utilities"
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb:do_compile () {
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb:  oe_runmake ${UBOOT_MACHINE}
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb:  oe_runmake envtools
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb:do_install () {
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb:  install -m 755 ${S}/tools/env/fw_printenv ${D}${base_sbindir}/fw_printenv
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb:  install -m 755 ${S}/tools/env/fw_printenv ${D}${base_sbindir}/fw_setenv
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb:do_install:class-cross () {
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb:  install -m 755 ${S}/tools/env/fw_printenv ${D}${bindir_cross}/fw_printenv
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb:  install -m 755 ${S}/tools/env/fw_printenv ${D}${bindir_cross}/fw_setenv
meta-nuvoton/recipes-bsp/u-boot/u-boot-fw-utils-nuvoton_git.bb: sysroot_stage_dir ${D}${bindir_cross} ${SYSROOT_DESTDIR}${bindir_cross}
meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc:do_configure () {
meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc:            oe_runmake -C ${S} O=${B} ${UBOOT_MACHINE}
meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc:            oe_runmake -C ${S} O=${B} oldconfig
meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc:do_compile () {
meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc:                    oe_runmake -C ${S} O=${B}/${config} ${config}
meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc:                    oe_runmake -C ${S} O=${B}/${config} ${UBOOT_MAKE_TARGET}
meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc:        oe_runmake -C ${S} O=${B} ${UBOOT_MAKE_TARGET}
meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc:do_install () {
meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc:do_deploy () {
meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc:addtask deploy before do_build after do_compile
```

Change-Id: Ic6969f12049c0d843009c4b754ab87ecff568a07
Signed-off-by: Willy Tu <wltu@google.com>
diff --git a/meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc b/meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc
index 60c722d..40fb5ad 100644
--- a/meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc
+++ b/meta-nuvoton/recipes-bsp/u-boot/u-boot-nuvoton.inc
@@ -228,7 +228,7 @@
 
 }
 
-FILES_${PN} = "/boot ${sysconfdir} ${datadir}"
+FILES:${PN} = "/boot ${sysconfdir} ${datadir}"
 
 do_deploy () {
     if [ -n "${UBOOT_CONFIG}" ]