pinctrl: bcm2835: Add support for wake-up interrupts

Leverage the IRQCHIP_MASK_ON_SUSPEND flag in order to avoid having to
specifically treat the GPIO interrupts during suspend and resume, and
simply implement an irq_set_wake() callback that is responsible for
enabling the parent wake-up interrupt as a wake-up interrupt.

To avoid allocating unnecessary resources for other chips, the wake-up
interrupts are only initialized if we have a brcm,bcm7211-gpio
compatibility string.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20200531001101.24945-5-f.fainelli@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>