net: stmmac: xgmac: Fix RSS not writing all Keys to HW

The sizeof(cfg->key) is != ARRAY_SIZE(cfg->key). Fix it. This warning is
triggered when running with cc flag -Wsizeof-array-div.
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Fixes: 76067459 ("net: stmmac: Implement RSS and enable it in XGMAC core")
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Jose Abreu <Jose.Abreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c

@@ -533,7 +533,7 @@ static int dwxgmac2_rss_configure(struct mac_device_info *hw,
 		return 0;
 	}
 
-	for (i = 0; i < (sizeof(cfg->key) / sizeof(u32)); i++) {
+	for (i = 0; i < (ARRAY_SIZE(cfg->key) / sizeof(u32)); i++) {
 		ret = dwxgmac2_rss_write_reg(ioaddr, true, i, cfg->key[i]);
 		if (ret)
 			return ret;