gpio: intel-mid: Remove driver for deprecated platform

gpio: intel-mid: Remove driver for deprecated platform

Intel Moorestown and Medfield are quite old Intel Atom based
32-bit platforms, which were in limited use in some Android phones,
tablets and consumer electronics more than eight years ago.

There are no bugs or problems ever reported outside from Intel
for breaking any of that platforms for years. It seems no real
users exists who run more or less fresh kernel on it. The commit
05f4434bc130 ("ASoC: Intel: remove mfld_machine") also in align
with this theory.

Due to above and to reduce a burden of supporting outdated drivers
we remove the support of outdated platforms completely.

Moreover this code duplicates gpio-pxa since the IP has been derived
from XScale implementation. If anybody wants to resurrect this
it has to be part of gpio-pxa.c.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>