arm: realm: Set RIPAS state for RAM

A Realm must ensure that the "RAM" region is set to RIPAS_RAM, before any
access is made. This patch makes sure that all memory blocks are marked as
RIPAS_RAM. Also, before we relocate the "FDT" and "initrd", make sure the
target location is marked too. This happens before we parse the memory blocks.

It is OK to do this operation on a given IPA multiple times. So, we don't
exclude the inital image areas from the "target" list.

Also, this operation doesn't require the host to commit physical memory to back
the IPAs yet. It can be done on demand via fault handling.

Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>