Xilinx: ARM: Copying gic.c from mainline.

gic_set_cpu caused compilation warnings regarding type mismatches between a
raw_spin_lock used with spin_lock functions.
The function does not seem to be called from anywhere and is not present in
mainline.
This patch simply overwrites arch/arm/common/gic.c with the version from
mainline.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>