Revert "upgrade: support upgrading ATF images"

This reverts commit 97a0f462.

package/base-files/files/lib/upgrade/iopsys.sh

@@ -332,12 +332,7 @@ iopsys_do_upgrade() {
 
 	if [ "$UPGRADE_OPT_FORCE_LOADER_UPGRADE" = "1" ]; then
 		log "sysupgrade" "Bootloader upgrade is enabled."
-		if fdtextract -l "$image" | grep -qF "atf"; then
-			iopsys_write_fit_image_component "$image" atf required mtd BL2            || return
-			iopsys_write_fit_image_component "$image" bootloader required mtd FIP     || return
-		else
-			iopsys_write_fit_image_component "$image" bootloader optional mtd u-boot  || return
-		fi
+		iopsys_write_fit_image_component "$image" bootloader optional mtd u-boot          || return
 	else
 		log "sysupgrade" "Bootloader upgrade is disabled."
 	fi