ARM: gic: Allow gic arch extensions to provide irqchip flags

Tegra can benefit from the IRQCHIP_MASK_ON_SUSPEND flag, allow it
to be passed to the gic irq chip.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-and-Acked-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Vishwanath BS <vishwanath.bs@ti.com>