HID: Accutouch: Add driver for ELO Accutouch 2216 USB Touchscreens

The Accutouch 2216 is reporting BTN_LEFT/BTN_MOUSE rather than BTM_TOUCH
in it's capabilities, which is what user space expects a touchscreen
device to report. This is causing udev to consider the device to be a
"VMware's USB mouse" rather than as a touchscreen, which results in a
mouse cursor being displayed in Weston.

This patch adds a special driver for the device to correct the
capabilities reported.

Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>