Tegra: per-CPU GIC CPU interface init

This patch enables per-CPU GIC CPU interfaces during CPU
power on. The previous code initialized the distributor
for all CPUs, which was not required.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
Change-Id: Ifd957b2367da06405b4c3e2225411adbaec35bb8