linux-wandboard

MLK-17290-04 gpio: mxc: add runtime pm support

Add runtime pm support to automatically enable the ipg clock and power
domain if present.

To save power, suggest all sub-devices of the gpiochip/irq domain should
dynamically manage gpio/irq resouces like:
gpio:
	gpiod_request()
	... //set gpio direction
	gpiod_free()
irq:
	devm_request_irq() //=> module active
	devm_free_irq() //=>module is non-active or runtime idle

Since the driver support irqchip and gpiochip, any irq/gpio resouce requested
by other modules the gpio controller clock and power domain should be enabled.
And the irqchip's parent's clock and power also should be enabled if irq resouce
requested.

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Tested-by: Guoniu.Zhou <guoniu.zhou@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>