platform-drivers-x86: convert drivers/platform/x86/* to use module_platform_driver()

This patch converts the drivers in drivers/platform/x86/* to use the
module_platform_driver() macro which makes the code smaller and a bit
simpler.

Cc: Hong Liu <hong.liu@intel.com>
Cc: Durgadoss R <durgadoss.r@intel.com>
Cc: Daniel Drake <dsd@laptop.org>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>