HID: multitouch: Add egalax ID for Acer Iconia W500

This patch adds USB ID for the touchpanel in Acer Iconia W500. The panel
supports up to five fingers, therefore the need for a new addition of panel
types.

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>