feat(gic600ae_fmu): enable all GICD, PPI, ITS SMs

The following SMIDs are disabled by default.

* GICD: MBIST REQ error and GICD FMU ClkGate override
* PPI: MBIST REQ error and PPI FMU ClkGate override
* ITS: MBIST REQ error and ITS FMU ClkGate override

This patch explicitly enables them during the FMU init sequence.

Change-Id: I573e64786e3318d4cbcd07d0a1caf25f8e6e9200
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>