HID: add support for two Waltop tablets

Add support for Waltop Slim Tablet 5.8 inch and Media Tablet 10.6 inch.

These (and other Waltop) tablets are usually sold by different companies
(such as Genius and Trust) and with different names, but with the same USB
vendor/product IDs.

Slim Tablet 5.8 inch is known to also be sold as Genius G-Pen F350 and Trust
Widescreen Mini Tablet (item no 16485).

Media Tablet 10.6 inch is known to also be sold as Genius G-Pen M609 and
M609X. Of these only the latter is known to be supported.

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