arm64: dts: fvp: Reserve 64MB for the FF-A firmware in memory map

Reserve 64MB of memory at the end of the first bank of DRAM on FVP model.
This is mainly for FF-A firmware use, as required by various firmware
configurations using the Firmware Framework for Arm (FF-A). This prevents
the kernel from overwriting the firmware region.

This is also useful when running other firmware configurations(non FF-A
based) that rely on usage of 64MB at the end of first DRAM bank.

Necessary for proper coexistence of firmware(FF-A partitions) and the OS.

Message-Id: <20250509154640.836093-3-sudeep.holla@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>