[media] media: Add mem2mem deinterlacing driver

Some video decoders such as tvp5150 provide separate
video fields (V4L2_FIELD_SEQ_TB/BT). This driver uses
dmaengine to convert this format to V4L2_FIELD_INTERLACED_TB/BT
(weaving) or V4L2_FIELD_NONE (line doubling) so that the
image can be displayed or processed.

Of course there will be combing effect in the image but this
can be accepted for some low quality applications.

Currently only YUV420 and YUYV formats are supported but
it can be extended later.

Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>