ArmPkg/ArmGic: Function to locate the current CPU GIC redistributor

ArmPkg/ArmGic: Function to locate the current CPU GIC redistributor

CPU GIC Registributors are located next to each other in the GIC Redistributor
space.
The CPU GIC Redistributor is identified by its CPU affinity Aff3.Aff2.Aff1.Aff0.

This function returns the base address of the GIC Redistributor of
the calling CPU.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <olivier.martin@arm.com>
Tested-by: Ard Biesheuvel <ard@linaro.org>
Reviewed-by: Ard Biesheuvel <ard@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16873 6f19259b-4bc3-4df7-8a09-765794883524