pinctrl: imx8mq: Add suspend/resume ops

To support pinctl hog restore after LPSR resume back,
add the generic suspend/resume in pinctrl-imx along with the
generic pm ops to be used by platform specific drivers. Then
make use of the newly added ops in i.MX8MQ platform specific
driver.

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Acked-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>