OMAP: DSS2: Support for Powertip PH480272T

Add support for Powertip PH480242T, a LCD 4.3inch (480x242) display
type with 24-bit RGB interface, 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>