HID: waltop: add Media Tablet 14.1 inch support

Add support for Waltop Media Tablet 14.1 inch by fixing report descriptor.

This tablet is also sold as Genius G-Pen M712 (older version) and M712X
(newer version). Both are supported.

Trust Wide Screen Design Tablet (TB-7300, item no 15358) seems to be the
older version of this tablet (similar to Genius G-Pen M712), and could be
supported as well.

Signed-off-by: Nikolai Kondrashov <spbnick@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>