pinctrl: samsung: fix suspend/resume functionality

The GPIO states need to be restored after s2r and this is not currently
supported in the pinctrl driver. This patch saves the gpio states before
suspend and restores them after resume.

Saving and restoring is done very early using syscore_ops and must
happen before pins are released from their powerdown state.

Patch originally from Prathyush K <prathyush.k@samsung.com> but
rewritten by Doug Anderson <dianders@chromium.org>.

Signed-off-by: Prathyush K <prathyush.k@samsung.com>
Signed-off-by: Doug Anderson <dianders@chromium.org>
Tested-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>