gpio: clean up Kconfig file

Fix multiple problems in punctuation, capitalization, grammar,
wording, and typos in the GPIO Kconfig file.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: linux-gpio@vger.kernel.org
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Sean Young <sean@mess.org>
Cc: Bamvor Jian Zhang <bamv2005@gmail.com>
Cc: Michael Walle <michael@walle.cc>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>