pinctrl: sirf: add power management support for atlas7

We had not implemented the pm interface of atlas7 pinctrl
and gpio drivers. So when system resumes from sleep, all
pin configuration and gpio status will be lost.

Now, we implement these interfaces to support pm.

At the same time, this patch also drops a lot of if-else
by look-up table for getting and setting pull.
Signed-off-by: Wei Chen <Wei.Chen@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>