net: stmmac: platform: Add snps,dwmac-5.20 IP compatible string

Add "snps,dwmac-5.20" compatible string for 5.20 version that can avoid
to define some platform data in the glue layer.
Tested-by: Tommaso Merciai <tomm.merciai@gmail.com>
Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Signed-off-by: Samin Guo <samin.guo@starfivetech.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

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

@@ -519,7 +519,8 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *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-4.20a") ||
-	    of_device_is_compatible(np, "snps,dwmac-5.10a")) {
+	    of_device_is_compatible(np, "snps,dwmac-5.10a") ||
+	    of_device_is_compatible(np, "snps,dwmac-5.20")) {
 		plat->has_gmac4 = 1;
 		plat->has_gmac = 0;
 		plat->pmt = 1;