intel_pmic_gpio: Make explicitly non-modular

The Kconfig entry controlling compilation of this code is:

drivers/platform/x86/Kconfig:config GPIO_INTEL_PMIC
drivers/platform/x86/Kconfig:   bool "Intel PMIC GPIO support"

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

We don't replace module.h with init.h since the file already has that.

Cc: Alek Du <alek.du@intel.com>
Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>