apm821xx: add support for the Cisco Meraki MR24

This patch adds support for the Cisco Meraki MR24 Access point
to the apm821xx target.

Board:		MR24 - Meraki MR24 Cloud Managed Access Point
CPU:		APM82181 SoC 800 MHz (PLB=200 OPB=100 EBC=100)
Flash size:	32MiB
RAM Size:	128MiB
Wireless:	Atheros AR9380 5.0GHz + Atheros AR9380 2.4GHz
Ethernet ports:	1x Gigabit Atheros AR8035

WARNING: The serial port needs a TTL/RS-232 v3.3 level converter!

For flashing instructions, visit:
<https://github.com/riptidewave93/Openwrt-MR24/blob/master/README.md#flashing>

Signed-off-by: Chris Blake <chrisrblake93@gmail.com>

target/linux/apm821xx/base-files/lib/upgrade/platform.sh

@@ -11,6 +11,11 @@ platform_check_image() {
 	[ "$#" -gt 1 ] && return 1
 
 	case "$board" in
+	mr24)
+		merakinand_do_platform_check $board "$1"
+		return $?;
+		;;
+
 	*)
 		;;
 	esac
@@ -23,6 +28,10 @@ platform_pre_upgrade() {
 	local board=$(apm821xx_board_name)
 
 	case "$board" in
+	mr24)
+		merakinand_do_upgrade "$1"
+		;;
+
 	*)
 		;;
 	esac