bcm53xx: sysupgrade: support Luxul NAND devices

This adds support for UBI-aware sysupgrade using Luxul formats.

Signed-off-by: Dan Haab <dan.haab@legrand.com>
(cherry picked from commit 63c43e5674f346b8ed13377d551e5699afbeb673)

target/linux/bcm53xx/base-files/lib/upgrade/platform.sh

@@ -402,6 +402,8 @@ platform_do_upgrade() {
 		case "$file_type" in
 			"chk")		platform_do_upgrade_nand_trx "$1" $((0x$(get_magic_long_at "$1" 4)));;
 			"cybertan")	platform_do_upgrade_nand_trx "$1" 32;;
+			"lxl")		platform_do_upgrade_nand_trx "$1" $(get_le_long_at "$1" 8);;
+			"lxlold")	platform_do_upgrade_nand_trx "$1" 64;;
 			"seama")	platform_do_upgrade_nand_seama "$1";;
 			"trx")		platform_do_upgrade_nand_trx "$1";;
 		esac