[media] s5p-mfc: improve v4l2_capability driver and card fields

[media] s5p-mfc: improve v4l2_capability driver and card fields

According to the V4L2 documentation the driver and card fields should be
used to identify the driver and the device but the s5p-mfc driver fills
those field using the platform device name, which in turn is the name of
the device DT node.

So not only the filled information isn't correct but also the same values
are used in all the fields for both the encoder and decoder video devices.

Before this patch:

Driver Info (not using libv4l2):
        Driver name   : 11000000.codec
        Card type     : 11000000.codec
        Bus info      : platform:11000000.codec
        Driver version: 4.7.0

Driver Info (not using libv4l2):
        Driver name   : 11000000.codec
        Card type     : 11000000.codec
        Bus info      : platform:11000000.codec
        Driver version: 4.7.0

After this patch:

Driver Info (not using libv4l2):
        Driver name   : s5p-mfc
        Card type     : s5p-mfc-dec
        Bus info      : platform:11000000.codec
        Driver version: 4.7.0

Driver Info (not using libv4l2):
        Driver name   : s5p-mfc
        Card type     : s5p-mfc-enc
        Bus info      : platform:11000000.codec
        Driver version: 4.7.0

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>