caif: Minor fixes in log prints.

Use pr_debug for flow control printouts, and refine an error printout.

Signed-off-by: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/caif/cfcnfg.c b/net/caif/cfcnfg.c
index ef93a13..41adafd1 100644
--- a/net/caif/cfcnfg.c
+++ b/net/caif/cfcnfg.c
@@ -197,7 +197,7 @@
 	caif_assert(adap_layer != NULL);
 	channel_id = adap_layer->id;
 	if (adap_layer->dn == NULL || channel_id == 0) {
-		pr_err("adap_layer->id is 0\n");
+		pr_err("adap_layer->dn == NULL or adap_layer->id is 0\n");
 		ret = -ENOTCONN;
 		goto end;
 	}