Add support for Wacom WACF007 and WACF008 to serial pnp driver

Notebook manufacturer seems to built a newer Wacom pen enabled tablet to
recent tablet pcs which are not recognized by the serial pnp driver.

Attached is a patch which makes the newer Wacom WACF007 and WACF008 tablets
useable with the serial driver.  The device is fully compatible with it.

Signed-off-by: Maik Broemme <mbroemme@plusserver.de>
Cc: Andrey Panin <pazke@orbita1.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>