USB: move routines in hcd.c

This patch (as939) moves a couple of routine in hcd.c around.  The
purpose is to put all the general URB- and endpoint-related routines
(submit, unlink, giveback, and disable) together in one spot.

There are no functional changes.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>