ssh1_rdpkt: remove a spurious crReturn.

Returning from the coroutine every time we finish putting together a
packet is wrong, because it means that any further data in the
incoming queue won't get processed until something triggers another
call to the coroutine. In ssh2_rdpkt I got this right - the only
crReturn that _isn't_ due to running out of data is the special one
immediately after a NEWKEYS - but I forgot to fix it the same way in
ssh1_rdpkt.

ssh.c

@@ -1602,7 +1602,6 @@ static void ssh1_rdpkt(Ssh ssh)
 
         pq_push(&ssh->pq_full, st->pktin);
         queue_idempotent_callback(&ssh->pq_full_consumer);
-        crReturnV;
     }
     crFinishV;
 }