ARM: davinci: dm644x evm: add support for VPBE display

This patch adds support for V4L2 video display to DM6446 EVM.

Support for SD and ED modes is provided, along with composite
and component outputs.

Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>