pinctrl: cix: sky1: Provide pin control dummy states

pinctrl: cix: sky1: Provide pin control dummy states

This exports and calls the pinctrl_provide_dummies() function from
the CIX SKY1 driver.

The reasons are explained in a comment in the commit, in essence the
two pin controllers need to go through explicit state transitions
default->sleep->default despite they only handle one single state
each.

Reviewed-by: Hans Zhang <hans.zhang@cixtech.com>
Reviewed-by: Fugang Duan <fugang.duan@cixtech.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>