cifs: fix wrong release in sess_alloc_buffer() failed path

smb_buf is allocated by small_smb_init_no_tc(), and buf type is
CIFS_SMALL_BUFFER, so we should use cifs_small_buf_release() to
release it in failed path.
Signed-off-by: Ding Hui <dinghui@sangfor.com.cn>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/sess.c

@@ -877,7 +877,7 @@ sess_alloc_buffer(struct sess_data *sess_data, int wct)
 	return 0;
 
 out_free_smb_buf:
-	kfree(smb_buf);
+	cifs_small_buf_release(smb_buf);
 	sess_data->iov[0].iov_base = NULL;
 	sess_data->iov[0].iov_len = 0;
 	sess_data->buf0_type = CIFS_NO_BUFFER;