mfd: sprd: Add wakeup capability for PMIC IRQ

When changing to use suspend-to-idle to save power, the PMIC irq can not
wakeup the system due to lack of wakeup capability, which will cause
the sub-irqs (such as power key) of the PMIC can not wake up the system.
Thus we can add the wakeup capability for PMIC irq to solve this issue,
as well as removing the IRQF_NO_SUSPEND flag to allow PMIC irq to be
a wakeup source.

Reported-by: Chunyan Zhang <zhang.lyra@gmail.com>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
Tested-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>