net: dsa: tag_qca: fix wrong MGMT_DATA2 size

It was discovered that MGMT_DATA2 can contain up to 28 bytes of data
instead of the 12 bytes written in the Documentation by accounting the
limit of 16 bytes declared in Documentation subtracting the first 4 byte
in the packet header.

Update the define with the real world value.

Tested-by: Ronald Wahl <ronald.wahl@raritan.com>
Fixes: c2ee8181fd ("net: dsa: tag_qca: add define for handling mgmt Ethernet packet")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Cc: stable@vger.kernel.org # v5.18+
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/dsa/tag_qca.h

@@ -45,8 +45,8 @@ struct sk_buff;
 					QCA_HDR_MGMT_COMMAND_LEN + \
 					QCA_HDR_MGMT_DATA1_LEN)
 
-#define QCA_HDR_MGMT_DATA2_LEN		12 /* Other 12 byte for the mdio data */
-#define QCA_HDR_MGMT_PADDING_LEN	34 /* Padding to reach the min Ethernet packet */
+#define QCA_HDR_MGMT_DATA2_LEN		28 /* Other 28 byte for the mdio data */
+#define QCA_HDR_MGMT_PADDING_LEN	18 /* Padding to reach the min Ethernet packet */
 
 #define QCA_HDR_MGMT_PKT_LEN		(QCA_HDR_MGMT_HEADER_LEN + \
 					QCA_HDR_LEN + \