fvp: add test group with 48-bit PA size

TFTF platform supports configurable PA size, in particular with tests
in the 48bit address range.
Adding a new test group and configurations to compile TFTF with 48bit
PA size and configure the model accordingly.

Signed-off-by: Federico Recanati <federico.recanati@arm.com>
Change-Id: Ic6499ae1903e3353831679c3b5c4bd2926032a9f
4 files changed