[media] davinci vpbe: V4L2 display driver for DM644X SoC

This is the display driver for Texas Instruments's DM644X family
SoC. This patch contains the main implementation of the driver with the
V4L2 interface. The driver implements the streaming model with
support for both kernel allocated buffers and user pointers. It also
implements all of the necessary IOCTLs necessary and supported by the
video display device.

Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
Acked-by: Muralidharan Karicheri <m-karicheri2@ti.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>