[media] davinci vpbe: VPBE display driver

This patch implements the core functionality of the display driver,
mainly controlling the VENC and other encoders, and acting as
the one point interface for the main V4L2 driver. This implements
the core of each of the V4L2 IOCTLs.

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>