This option makes it hard to optimize the memory definitions of all Arm
platforms because any change in the common defines must work in all of
them. The best thing to do is to remove it and move the definition to
each platform's header.

FVP, SGI and SGM were using the definitions in board_arm_def.h. The
definitions have been copied to each platform's platform_def.h. Juno
was already using the ones in platform_def.h, so there have been no
changes.

Change-Id: I9aecd11bbc72a3d0d7aad1ef9934d8df21dcfaf2
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>