HID: rmi: Support the Fujitsu R726 Pad dock using hid-rmi

The Fujitsu R726 Pad has an optional USB keyboard dock which contains
a Synaptics touchpad. The dock identifies itself as a
Primax Rezel Tablet Keyboard.

Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>