ARM: ux500: set proper GIC flags

The Ux500 will be able to wake up on any IRQ, so flag it with
IRQCHIP_SKIP_SET_WAKE, and we want to mask off the IRQs when
going to suspend to avoid transient effects so also flag
this with IRQCHIP_MASK_ON_SUSPEND.

Cc: Etienne Carriere <etienne.carriere@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>