css/sgi: remove redundant copy of gic driver data

Instead of instantiating a local copy of GICv3 driver data for SGI
platforms, reuse the existing instance of GICv3 driver data available
in the arm common platform code.

Change-Id: If6f38e15d1f0e20cea96fff98091da300015d295
Signed-off-by: Chandni Cherukuri <chandni.cherukuri@arm.com>
Signed-off-by: Vishwanatha HG <vishwanatha.hg@arm.com>
3 files changed