MIPS: do away with ARCH_[WANT_OPTIONAL|REQUIRE]_GPIOLIB

This replaces:

- "select ARCH_REQUIRE_GPIOLIB" with "select GPIOLIB" as this can
  now be selected directly.

- "select ARCH_WANT_OPTIONAL_GPIOLIB" with no dependency: GPIOLIB
  is now selectable by everyone, so we need not declare our
  intent to select it.

When ordering the symbols the following rationale was used:
if the selects were in alphabetical order, I moved select GPIOLIB
to be in alphabetical order, but if the selects were not
maintained in alphabetical order, I just replaced
"select ARCH_REQUIRE_GPIOLIB" with "select GPIOLIB".

Cc: Michael Büsch <m@bues.ch>
Cc: linux-mips@linux-mips.org
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>