USB: combine hub_quiesce and hub_stop

This patch (as1083) combines hub_quiesce() and hub_stop() into a
single routine.  There's no point keeping them separate since they are
usually called together.

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