media: mc: Improve unconnected pads debugging message in link exploration

When exploring links, a message is printed to indicate unconnected pads
being added. The message prints the entity name only. Print the origin
pad number as well to help with debugging pipeline start issues. While
at it, get the entity name from origin->entity instead of local->entity.
Both point to the same entity, but the former conveys the meaning
better.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>