fs/ntfs3: Refactor enum_rstbl to suppress static checker

Comments and brief description of function enum_rstbl added.

Fixes: b46acd6a ("fs/ntfs3: Add NTFS journal")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/fslog.c

@@ -609,14 +609,29 @@ static inline void add_client(struct CLIENT_REC *ca, u16 index, __le16 *head)
 	*head = cpu_to_le16(index);
 }
 
+/*
+ * Enumerate restart table.
+ *
+ * @t - table to enumerate.
+ * @c - current enumerated element.
+ *
+ * enumeration starts with @c == NULL
+ * returns next element or NULL
+ */
 static inline void *enum_rstbl(struct RESTART_TABLE *t, void *c)
 {
 	__le32 *e;
 	u32 bprt;
-	u16 rsize = t ? le16_to_cpu(t->size) : 0;
+	u16 rsize;
+
+	if (!t)
+		return NULL;
+
+	rsize = le16_to_cpu(t->size);
 
 	if (!c) {
-		if (!t || !t->total)
+		/* start enumeration. */
+		if (!t->total)
 			return NULL;
 		e = Add2Ptr(t, sizeof(struct RESTART_TABLE));
 	} else {