[PATCH] USB: fix usb wacom tablet driver bug

This patch fixes bug 4905 and a Cintiq 21UX bug.

Signed-off-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>