meta-phosphor: prep for new override syntax

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I588025b614416c43aa2d053765ab53bacf890cb5
diff --git a/meta-phosphor/recipes-phosphor/flash/phosphor-image-signing.bb b/meta-phosphor/recipes-phosphor/flash/phosphor-image-signing.bb
index 16e1d99..d10ecef 100644
--- a/meta-phosphor/recipes-phosphor/flash/phosphor-image-signing.bb
+++ b/meta-phosphor/recipes-phosphor/flash/phosphor-image-signing.bb
@@ -11,7 +11,7 @@
 DEPENDS += "openssl-native"
 DEPENDS += "${@oe.utils.conditional('INSECURE_KEY', 'True', 'phosphor-insecure-signing-key-native', '', d)}"
 
-FILES_${PN} += "${sysconfdir}/activationdata/"
+FILES:${PN} += "${sysconfdir}/activationdata/"
 
 SIGNING_KEY ?= "${STAGING_DIR_NATIVE}${datadir}/OpenBMC.priv"
 SIGNING_KEY_TYPE = "${@os.path.splitext(os.path.basename('${SIGNING_KEY}'))[0]}"
@@ -27,4 +27,4 @@
 	install -m 644 ${WORKDIR}/hashfunc ${idir}
 }
 
-SYSROOT_DIRS_append = " ${sysconfdir}"
+SYSROOT_DIRS:append = " ${sysconfdir}"