greybus: protocol: add a module owner to a protocol

Now that protocols can be in a module, we need to reference count them
to lock them into memory so they can't be removed while in use.  So add
a module owner structure, and have it automatically be assigned when
registering the protocol.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
Reviewed-by: Alex Elder <elder@linaro.org>