smb3: fix confusing debug message

The message said it was an invalid mode, when it was intentionally
not set.  Fix confusing message logged to dmesg.
Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/client/smb2pdu.c

@@ -848,7 +848,7 @@ add_posix_context(struct kvec *iov, unsigned int *num_iovec, umode_t mode)
 
 	iov[num].iov_base = create_posix_buf(mode);
 	if (mode == ACL_NO_MODE)
-		cifs_dbg(FYI, "Invalid mode\n");
+		cifs_dbg(FYI, "%s: no mode\n", __func__);
 	if (iov[num].iov_base == NULL)
 		return -ENOMEM;
 	iov[num].iov_len = sizeof(struct create_posix);