caif: Bugfix - XOFF removed channel from caif-mux

XOFF was mixed up with DOWN indication, causing causing CAIF channel to be
removed from mux and all incoming traffic to be lost after receiving flow-off.
Fix this by replacing FLOW_OFF with DOWN notification.
Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@conan.davemloft.net>

net/caif/cfmuxl.c

@@ -255,7 +255,7 @@ static void cfmuxl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 
 		if (cfsrvl_phyid_match(layer, phyid) && layer->ctrlcmd) {
 
-			if ((ctrl == _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND ||
+			if ((ctrl == _CAIF_CTRLCMD_PHYIF_DOWN_IND ||
 				ctrl == CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND) &&
 					layer->id != 0) {