greybus: interface: amend interface registration message

Amend the interface registration message with the detected interface
type, and only print the Ara VID/PID and DDBL1 attributes for the types
for which they exist.

Also drop the now redundant message about a detected dummy interface
from the activate operation helper.

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>