armv7: dts: ls1021a: Remove aliases property name warning

Remove aliases property name warning while compilation:
Warning (alias_paths): /aliases: aliases property name must
include only lowercase and '-'

Signed-off-by: Rajesh Bhagat <rajesh.bhagat@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>
diff --git a/arch/arm/dts/ls1021a-twr.dtsi b/arch/arm/dts/ls1021a-twr.dtsi
index 14e0cea..928e100 100644
--- a/arch/arm/dts/ls1021a-twr.dtsi
+++ b/arch/arm/dts/ls1021a-twr.dtsi
@@ -11,9 +11,9 @@
 	model = "LS1021A TWR Board";
 
 	aliases {
-		enet2_rgmii_phy = &rgmii_phy1;
-		enet0_sgmii_phy = &sgmii_phy2;
-		enet1_sgmii_phy = &sgmii_phy0;
+		enet2-rgmii-phy = &rgmii_phy1;
+		enet0-sgmii-phy = &sgmii_phy2;
+		enet1-sgmii-phy = &sgmii_phy0;
 		spi0 = &qspi;
 		spi1 = &dspi1;
 	};