ARM: dts: k2g-evm: Use standard compatible string for USB no-op PHY

The standard compatible string is "usb-nop-xceiv", use it.
Note that keystone-k2g.dtsi already uses the aforementioned
compat string, so this patch can only remove the override.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexey Brodkin <alexey.brodkin@synopsys.com>
Cc: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Jean-Jacques Hiblot <jjhiblot@ti.com>
Cc: Murali Karicheri <m-karicheri2@ti.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Ye Li <ye.li@nxp.com>
Cc: uboot-imx <uboot-imx@nxp.com>
diff --git a/arch/arm/dts/keystone-k2g-evm.dts b/arch/arm/dts/keystone-k2g-evm.dts
index 7c5deef..b5b511c 100644
--- a/arch/arm/dts/keystone-k2g-evm.dts
+++ b/arch/arm/dts/keystone-k2g-evm.dts
@@ -38,7 +38,6 @@
 
 &usb0_phy {
 	status = "okay";
-	compatible = "nop-phy";
 };
 
 &usb0 {
@@ -51,7 +50,6 @@
 };
 
 &usb1_phy {
-	compatible = "nop-phy";
 	status = "okay";
 };