[media] davinci: vpfe: add v4l2 video driver support

[media] davinci: vpfe: add v4l2 video driver support

Add a generic video driver functionality to be used by all the vpfe
drivers for davinci SoCs. The functionality includes all the
standard v4l2 interfaces including streaming. The video node
interface can be used both as an input and output node for both
continuous and single shot modes. Also supports dv_presets to include
HD modes, wth support for both user pointer IO and mmap. The buffering
mechanism is based on videobuf2 interface.

Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>