net: stmmac: add dwmac-4.20a compatible

Manage dwmac-4.20a version from synopsys
Signed-off-by: Christophe Roullier <christophe.roullier@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -472,7 +472,8 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 	}
 
 	if (of_device_is_compatible(np, "snps,dwmac-4.00") ||
-	    of_device_is_compatible(np, "snps,dwmac-4.10a")) {
+	    of_device_is_compatible(np, "snps,dwmac-4.10a") ||
+	    of_device_is_compatible(np, "snps,dwmac-4.20a")) {
 		plat->has_gmac4 = 1;
 		plat->has_gmac = 0;
 		plat->pmt = 1;