staging: bcm2835-codec: Add role to device name

Three entities are created, Decode, Encode and ISP but all of the video
nodes use the same video name string "bcm2835-codec" which makes it
difficult to identify each role.

Append the role-name to the video name to facilitate identifying a
specific instance from userspace.

The Card-Type is also extended with the role name to support identifying
the device context from within QUERY_CAP operations.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>