rock-3a: unset BOOTFS_TYPE for non-vendor builds

Author: EvilOlaf

config/boards/rock-3a.conf

@@ -25,6 +25,7 @@ function post_family_config__rock-3a_use_mainline_uboot_except_vendor_and_add_sa
 	[[ "${BRANCH}" == "vendor" ]] && return 0
 
 	display_alert "$BOARD" "Mainline U-Boot overrides for $BOARD - $BRANCH" "info"
+	unset BOOTFS_TYPE
 	declare -g BOOTCONFIG="rock-3a-rk3568_defconfig"
 	declare -g BOOTDELAY=1
 	declare -g BOOTSOURCE="https://github.com/u-boot/u-boot"