OMAP: DSS2: Support for Seiko 70WVW1TZ3

Add support for Seiko 70WVW1TZ3, a LCD 7.0inch WVGA (800x480) display
type with 24-bit RGB interface and Touch-Panel, to panel-generic-dpi

Tested with IGEP v2 board.

Signed-off-by: Enric Balletbo i Serra <eballetbo@iseebcn.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>