net: openvswitch: fix kernel-doc warnings in flow.c

Repair kernel-doc notation in a few places to make it conform to
the expected format.

Fixes the following kernel-doc warnings:

flow.c:296: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 * Parse vlan tag from vlan header.
flow.c:296: warning: missing initial short description on line:
 * Parse vlan tag from vlan header.
flow.c:537: warning: No description found for return value of 'key_extract_l3l4'
flow.c:769: warning: No description found for return value of 'key_extract'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Pravin B Shelar <pshelar@ovn.org>
Cc: dev@openvswitch.org
Link: https://lore.kernel.org/r/20210808190834.23362-1-rdunlap@infradead.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/openvswitch/flow.c

@@ -293,14 +293,14 @@ static bool icmp6hdr_ok(struct sk_buff *skb)
 }
 
 /**
- * Parse vlan tag from vlan header.
+ * parse_vlan_tag - Parse vlan tag from vlan header.
  * @skb: skb containing frame to parse
  * @key_vh: pointer to parsed vlan tag
  * @untag_vlan: should the vlan header be removed from the frame
  *
- * Returns ERROR on memory error.
- * Returns 0 if it encounters a non-vlan or incomplete packet.
- * Returns 1 after successfully parsing vlan tag.
+ * Return: ERROR on memory error.
+ * %0 if it encounters a non-vlan or incomplete packet.
+ * %1 after successfully parsing vlan tag.
  */
 static int parse_vlan_tag(struct sk_buff *skb, struct vlan_head *key_vh,
 			  bool untag_vlan)
@@ -532,6 +532,7 @@ static int parse_nsh(struct sk_buff *skb, struct sw_flow_key *key)
  *       L3 header
  * @key: output flow key
  *
+ * Return: %0 if successful, otherwise a negative errno value.
  */
 static int key_extract_l3l4(struct sk_buff *skb, struct sw_flow_key *key)
 {
@@ -748,8 +749,6 @@ static int key_extract_l3l4(struct sk_buff *skb, struct sw_flow_key *key)
  *
  * The caller must ensure that skb->len >= ETH_HLEN.
  *
- * Returns 0 if successful, otherwise a negative errno value.
- *
  * Initializes @skb header fields as follows:
  *
  *    - skb->mac_header: the L2 header.
@@ -764,6 +763,8 @@ static int key_extract_l3l4(struct sk_buff *skb, struct sw_flow_key *key)
  *
  *    - skb->protocol: the type of the data starting at skb->network_header.
  *      Equals to key->eth.type.
+ *
+ * Return: %0 if successful, otherwise a negative errno value.
  */
 static int key_extract(struct sk_buff *skb, struct sw_flow_key *key)
 {