pinctrl: gemini: Mask and set properly

The code was written under the assumption that the
regmap_update_bits() would mask the bits in the mask and
set the bits in the value.

It missed the points that it will not set bits in the value
unless these are also masked in the mask. Set value bits
that are not in the mask will simply be ignored.

Fixes: 06351d13 ("pinctrl: add a Gemini SoC pin controller")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>