mach-k3: am64_spl: Alias Ethernet RGMII boot to CPGMAC

This is required to enables spl_net boot on AM64x

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
diff --git a/arch/arm/mach-k3/include/mach/am64_spl.h b/arch/arm/mach-k3/include/mach/am64_spl.h
index 607b09c..b4f396b 100644
--- a/arch/arm/mach-k3/include/mach/am64_spl.h
+++ b/arch/arm/mach-k3/include/mach/am64_spl.h
@@ -12,6 +12,7 @@
 #define BOOT_DEVICE_QSPI		0x02
 #define BOOT_DEVICE_SPI			0x03
 #define BOOT_DEVICE_ETHERNET		0x04
+#define BOOT_DEVICE_CPGMAC		0x04
 #define BOOT_DEVICE_ETHERNET_RGMII	0x04
 #define BOOT_DEVICE_ETHERNET_RMII	0x05
 #define BOOT_DEVICE_I2C			0x06