V4L/DVB (12906c): V4L : vpif capture driver for DM6467

This is the vpif capture bridge driver for DM6467.  This video
supports two video channels each having a tvp5147 device at
the input. This allows simultaneous capture of NTSC/PAL video
in each of this channel. Both MMAP and USERPTR io mechanism
are supported. Currently buffer allocation happens at REQBUF
ioctl request. Since USERPTR IO is supported, this is not an
issue since user applications can allocate buffers and pass
the user space address to the driver. Following are TODOs :-
	1) Adding support for allocation of buffers at init
	2) VBI/HBI data service

This has incorporated comments received against version v0
of the patch series.

Resending to merge V4l linux-next
 create mode 100644 drivers/media/video/davinci/vpif_capture.c
 create mode 100644 drivers/media/video/davinci/vpif_capture.h

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