pinctrl: samsung: Allow pin value to be initialized using pinfunc

This patch extends the range of settings configurable via pinfunc API
to cover pin value as well. This allows configuration of default values
of pins, which is useful for pins that are not supposed to be used by
any dedicated driver, but need certain board-specific setting.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>