greybus: drop hd arg from submit_gbuf method

greybus: drop hd arg from submit_gbuf method

Every gbuf is associated with a connection when it is created.  And
a connection contains a pointer to the host device that will carry
messages.  So there's no need for the submit_gbuf() method to have
the host device pointer passed to it, the function can get it from
the gbuf's connection.

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