platform/x86/intel: Remove X86_PLATFORM_DRIVERS_INTEL

While introduction of this menu brings a nice view in the configuration tools,
it brought more issues than solves, i.e. it prevents to locate files in the
intel/ subfolder without touching non-related Kconfig dependencies elsewhere.
Drop X86_PLATFORM_DRIVERS_INTEL altogether.

Note, on x86 it's enabled by default and it's quite unlikely anybody wants to
disable all of the modules in this submenu.

Fixes: 8bd836fe

 ("platform/x86: intel_skl_int3472: Move to intel/ subfolder")
Suggested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211222194941.76054-1-andriy.shevchenko@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>