pinctrl: samsung: Add infrastructure for pin-bank retention control

Pad retention control after suspend/resume cycle should be done from pin
controller driver instead of PMU (power management unit) driver to avoid
possible ordering and logical dependencies. Till now it worked fine only
because PMU driver registered its sys_ops after pin controller.

This patch adds infrastructure to handle pad retention during pin control
driver resume.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>