octeontx2-pf: Do not modify number of rules

In the ETHTOOL_GRXCLSRLALL ioctl ethtool uses
below structure to read number of rules from the driver.

    struct ethtool_rxnfc {
            __u32                           cmd;
            __u32                           flow_type;
            __u64                           data;
            struct ethtool_rx_flow_spec     fs;
            union {
                    __u32                   rule_cnt;
                    __u32                   rss_context;
            };
            __u32                           rule_locs[0];
    };

Driver must not modify rule_cnt member. But currently driver
modifies it by modifying rss_context. Hence fix it by using a
local variable.

Fixes: 81a4362 ("octeontx2-pf: Add RSS multi group support")
Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/octeontx2/nic/otx2_flows.c

@@ -257,17 +257,19 @@ int otx2_get_flow(struct otx2_nic *pfvf, struct ethtool_rxnfc *nfc,
 int otx2_get_all_flows(struct otx2_nic *pfvf, struct ethtool_rxnfc *nfc,
 		       u32 *rule_locs)
 {
+	u32 rule_cnt = nfc->rule_cnt;
 	u32 location = 0;
 	int idx = 0;
 	int err = 0;
 
 	nfc->data = pfvf->flow_cfg->ntuple_max_flows;
-	while ((!err || err == -ENOENT) && idx < nfc->rule_cnt) {
+	while ((!err || err == -ENOENT) && idx < rule_cnt) {
 		err = otx2_get_flow(pfvf, nfc, location);
 		if (!err)
 			rule_locs[idx++] = location;
 		location++;
 	}
+	nfc->rule_cnt = rule_cnt;
 
 	return err;
 }