Bump skiboot to 5.3.0 for all platforms

Post op-build v1.10, we're bringing all platforms up to latest skiboot.

Effectively, 5.2.x won't be maintained unless somebody steps up to do it.

See the skiboot release notes for changes:
https://github.com/open-power/skiboot/blob/skiboot-5.3.0/doc/release-notes/skiboot-5.3.0.txt
https://github.com/open-power/skiboot/blob/skiboot-5.3.0/doc/release-notes/skiboot-5.3.0-rc1.txt
https://github.com/open-power/skiboot/blob/skiboot-5.3.0/doc/release-notes/skiboot-5.3.0-rc2.txt

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
diff --git a/openpower/configs/firenze_defconfig b/openpower/configs/firenze_defconfig
index b18aa35..dcf6d70 100644
--- a/openpower/configs/firenze_defconfig
+++ b/openpower/configs/firenze_defconfig
@@ -22,11 +22,7 @@
 
 BR2_TARGET_GENERIC_HOSTNAME="skiroot"
 
-# skiboot will be built but we don't need embedded payload
 BR2_PACKAGE_SKIBOOT=y
-BR2_PACKAGE_SKIBOOT_EMBED_PAYLOAD=n
-BR2_SKIBOOT_CUSTOM_VERSION=y
-BR2_SKIBOOT_CUSTOM_VERSION_VALUE="skiboot-5.3.0"
 
 # petitboot requirements
 BR2_ENABLE_LOCALE_PURGE=y
diff --git a/openpower/configs/garrison_defconfig b/openpower/configs/garrison_defconfig
index 370e243..f79f78e 100644
--- a/openpower/configs/garrison_defconfig
+++ b/openpower/configs/garrison_defconfig
@@ -31,10 +31,6 @@
 
 BR2_TARGET_GENERIC_HOSTNAME="skiroot"
 
-# skiboot requirements
-BR2_SKIBOOT_CUSTOM_VERSION=y
-BR2_SKIBOOT_CUSTOM_VERSION_VALUE="skiboot-5.3.0"
-
 # petitboot requirements
 BR2_ENABLE_LOCALE_PURGE=y
 BR2_ENABLE_LOCALE_WHITELIST="C de en es fr it ja ko pt_BR ru zh_CN zh_TW"
diff --git a/openpower/configs/openpower_p9_mambo_defconfig b/openpower/configs/openpower_p9_mambo_defconfig
index f7672a4..7dfbf8b 100644
--- a/openpower/configs/openpower_p9_mambo_defconfig
+++ b/openpower/configs/openpower_p9_mambo_defconfig
@@ -41,6 +41,4 @@
 # BR2_PACKAGE_OPENPOWER_PNOR is not set
 BR2_OPENPOWER_CONFIG_NAME="openpower-mambo-p9"
 BR2_PACKAGE_PETITBOOT=y
-# BR2_PACKAGE_OCC is not set
-BR2_SKIBOOT_CUSTOM_VERSION=y
-BR2_SKIBOOT_CUSTOM_VERSION_VALUE="skiboot-5.3.0"
+# BR2_PACKAGE_OCC is not set
\ No newline at end of file
diff --git a/openpower/package/skiboot/Config.in b/openpower/package/skiboot/Config.in
index be8370e..551c81b 100644
--- a/openpower/package/skiboot/Config.in
+++ b/openpower/package/skiboot/Config.in
@@ -31,7 +31,7 @@
 
 config BR2_SKIBOOT_VERSION
 	string
-	default "skiboot-5.2.5" if BR2_SKIBOOT_LATEST_VERSION
+	default "skiboot-5.3.0" if BR2_SKIBOOT_LATEST_VERSION
 	default BR2_SKIBOOT_CUSTOM_VERSION_VALUE \
 		if BR2_SKIBOOT_CUSTOM_VERSION