pinctrl: sirf: switch to using allocated state container

This rewrites the SIRF pinctrl driver to allocate a state container
for the GPIO chip, just as is done for the pin controller, and
use the gpiochip_add_pin_range() to add the range from the gpiochip
side rather than adding the range from the pinctrl side.

All resulting changes are done in order to pass around a state
container rather than refer to a static global object.

Acked-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>