meta-nuvoton: add support to generate full flash image for npcm8xx

Nuvoton's npcm8xx full flash image includes TIP FW, Bootblock,
ATF, OPTEE and UBOOT with headers. Generating headers and merging
images are being done by Nuvoton's binary generator tool (Bingo)
which uses external parameters from XML files for that.
Thus, we need to add related fitimage and image type for npcm8xx.

However, before merge this commit, we must wait for below commits were merged.

meta-nuvoton: arm-trusted-firmware: add arm trusted firmware recipe
https://gerrit.openbmc.org/c/openbmc/openbmc/+/55234

meta-nuvoton: add npcm8xx-bootblock recipe
https://gerrit.openbmc.org/c/openbmc/openbmc/+/55117

meta-nuvoton: add npcm8xx-igps recipe
https://gerrit.openbmc.org/c/openbmc/openbmc/+/55099

meta-nuvoton: npcm7xx-bingo: upgrade latest version 0.0.5 support Arbel
https://gerrit.openbmc.org/c/openbmc/openbmc/+/55128

Signed-off-by: Tim Lee <timlee660101@gmail.com>
Change-Id: I4599e39d3873f07cde6904d0f10161964fc45c7a
diff --git a/meta-phosphor/conf/distro/include/phosphor-base.inc b/meta-phosphor/conf/distro/include/phosphor-base.inc
index 2af46f9..13e3065 100644
--- a/meta-phosphor/conf/distro/include/phosphor-base.inc
+++ b/meta-phosphor/conf/distro/include/phosphor-base.inc
@@ -116,6 +116,7 @@
 
 IMAGE_CLASSES:append = " image_types_phosphor phosphor-rootfs-postcommands"
 IMAGE_CLASSES:append:npcm7xx = " image_types_phosphor_nuvoton"
+IMAGE_CLASSES:append:npcm8xx = " image_types_phosphor_nuvoton_npcm8xx"
 
 IMAGE_INSTALL:append = " dbus-broker libnss-systemd"