platform/x86: x86-android-tablets: Move into its own subdir

Move the x86-android-tablets code into its own subdir, this is
a preparation patch for splitting the somewhat large file into
multiple smaller files.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20230301092331.7038-3-hdegoede@redhat.com