[L] Change in coreboot[main]: mb/arm/rdn2: Add support for Arm Neoverse N2

[Naresh Solanki (Code Review)]

Attention is currently required from: Angel Pons, Arthur Heymans, David Milosevic, Maximilian Brune, Nico Huber, Patrick Rudolph, Paul Menzel.

Naresh Solanki has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/79103?usp=email )

Change subject: mb/arm/rdn2: Add support for Arm Neoverse N2
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Patch Set 2:

(1 comment)

File src/mainboard/arm/rdn2/mainboard.c:

https://review.coreboot.org/c/coreboot/+/79103/comment/ceab570c_74c1f67b :
PS2, Line 22: 	return (size_t)probe_ramsize((uintptr_t)RDN2_DRAM2_BASE, RDN2_DRAM2_SIZE) * MiB;
> reference firmware by default uses 6GB RAM for  DRAM2 unless overridden by build parameter CFLAGS=-D […]

Memory info isn't available via TF pointers for Neoverse N2.
Hence RAM has to be probed for now. tested to work without any issues.