pinctrl: add a driver for the CSR SiRFprimaII pinmux

This creates a pin controller driver for the SiRFprinaII
pin mux portions.

Signed-off-by: Rongjun Ying <Rongjun.Ying@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
[Fixup for changed function names and semantics in the v10 patch]
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>