pinctrl: sirf: make core support explicitly non-modular

The Makefile currently controlling compilation of this code is:

  drivers/pinctrl/sirf/pinctrl-sirf.o
      --> drivers/pinctrl/sirf/Makefile:obj-y += pinctrl-sirf.o

...meaning that it currently is not being built as a module by anyone.

Lets remove the couple traces of modular infrastructure use, so that
when reading the driver there is no doubt it is builtin-only.

We also delete the MODULE_LICENSE tag etc. since all that information
was (or is now) contained at the top of the file in the comments.

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Rongjun Ying <rongjun.ying@csr.com>
Cc: Yuping Luo <yuping.luo@csr.com>
Cc: Barry Song <baohua@kernel.org>
Cc: linux-gpio@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>