media: cec: name for RC passthrough device does not need 'RC for'

An RC device is does not need to be called 'RC for'. Simply the name
will suffice.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>