am43xx_evm: add eth boot support

add cpsw ethernet boot mode support to download spl and
u-boot.img via tftp protocol. Also adding a seperate config
for ethernet boot mode as the default build falcon mode and
environment on MMC is defined for ethernet boot mode
environment should be set to nowhere.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/am43xx_evm_ethboot_defconfig b/configs/am43xx_evm_ethboot_defconfig
new file mode 100644
index 0000000..5b07cc1
--- /dev/null
+++ b/configs/am43xx_evm_ethboot_defconfig
@@ -0,0 +1,5 @@
+CONFIG_ARM=y
+CONFIG_TARGET_AM43XX_EVM=y
+CONFIG_SPL=y
+CONFIG_SYS_EXTRA_OPTIONS="SERIAL1,CONS_INDEX=1,NAND,SPL_ETH_SUPPORT"
+CONFIG_CMD_NET=y