ARM: dts: keystone-k2hk: Reserve MSM RAM for boot monitor

ARM: dts: keystone-k2hk: Reserve MSM RAM for boot monitor

The Keystone 2 boot monitor uses 32 KB of the MSM RAM @ 0x0c5f0000
on 66AK2H SoCs, so add a reserved child node for the same.

This address is aligned to the values used within the latest boot
monitor firmware [1] as of commit cf8b431e8b3b ("soc: Move load
address to end of MSMC").

[1] git://git.ti.com/processor-firmware/ks2-boot-monitor.git

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>