arm/tegra: Remove code that's ifndef CONFIG_ARM_GIC

entry-macro.S contains some stale code for chips before Tegra20 that
apparently didn't use an ARM GIC. All chips supported by mainline use
an ARM GIC, so rip out the stale code.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Olof Johansson <olof@lixom.net>