Add dt bindings document for pinmux & GPIO controller driver of
Intel Lightning Mountain SoC.
Signed-off-by: Rahul Tanwar <rahul.tanwar@linux.intel.com>
Link: https://lore.kernel.org/r/b59afc497e41404fea06aa48d633cba183ee944d.1573797249.git.rahul.tanwar@linux.intel.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>