feat(plat/fvp): add EL3 SPMC #defines

Introduce additional #defines for running with the EL3
SPMC on the FVP.

The increase in xlat tables has been chosen to allow
the test cases to complete successfully and may need
adjusting depending on the desired usecase.

Signed-off-by: Marc Bonnici <marc.bonnici@arm.com>
Change-Id: I7f44344ff8b74ae8907d53ebb652ff8def2d2562