pinctrl: samsung: Save/restore eint_mask over suspend for EINT_TYPE GPIOs

Currently, for EINT_TYPE GPIOs, the CON and FLTCON registers
are saved and restored over a suspend/resume cycle.  However, the
EINT_MASK registers are not.

On S5PV210 at the very least, these registers are not retained over
suspend, leading to the interrupts remaining masked upon resume and
therefore no interrupts being triggered for the device.  There should
be no effect on any SoCs that do retain these registers as theoretically
we would just be re-writing what was already there.

Fixes: 7ccbc60c ("pinctrl: exynos: Handle suspend/resume of GPIO EINT registers")
Cc: <stable@vger.kernel.org>
Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>