irqchip/qcom-pdc: Set IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND flag

Set IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND flag to enable/unmask the
wakeirqs during suspend entry.

Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/1601267524-20199-6-git-send-email-mkshah@codeaurora.org