platform/x86: Add include/linux/platform_data/x86 to MAINTAINERS

Most of the files there are being used under PDx86 subsystem or
tightly related drivers (like drivers/clk/x86/). I think it makes
sense to assure that PDx86 keeps an eye on the changes there.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230206150202.27892-1-andriy.shevchenko@linux.intel.com


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>