base-files: bring back nand_do_upgrade_success

Several Broadcom targets were using the nand_do_upgrade_success
shell function which has been removed by commit e25e6d8e54
("base-files: fix and clean up nand sysupgrade code"). Refactor the
new nand_do_upgrade to bring back nand_do_upgrade_success with the
behavior expected by those users.

Fixes: e25e6d8e54 ("base-files: fix and clean up nand sysupgrade code")
Reported-by: Chen Minqiang <[email protected]>
Signed-off-by: Daniel Golle <[email protected]>

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

@@ -418,12 +418,20 @@ nand_do_upgrade() {
 	local file="$1"
 
 	sync
-	if nand_do_flash_file "$file" && nand_do_restore_config && sync; then
+	nand_do_flash_file "$file" && nand_do_upgrade_success
+	nand_do_upgrade_failed
+}
+
+nand_do_upgrade_success() {
+	if nand_do_restore_config && sync; then
 		echo "sysupgrade successful"
 		umount -a
 		reboot -f
 	fi
+	nand_do_upgrade_failed
+}
 
+nand_do_upgrade_failed() {
 	sync
 	echo "sysupgrade failed"
 	# Should we reboot or bring up some failsafe mode instead?