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>

configs/am43xx_evm_ethboot_defconfig

+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

include/configs/am43xx_evm.h

@@ -317,11 +317,11 @@
 
 #endif
 
+#ifndef CONFIG_SPL_BUILD
 /* CPSW Ethernet */
 #define CONFIG_CMD_DHCP
 #define CONFIG_CMD_PING
 #define CONFIG_CMD_MII
-#define CONFIG_DRIVER_TI_CPSW
 #define CONFIG_MII
 #define CONFIG_BOOTP_DEFAULT
 #define CONFIG_BOOTP_DNS
@@ -331,13 +331,20 @@
 #define CONFIG_BOOTP_SUBNETMASK
 #define CONFIG_NET_RETRY_COUNT		10
 #define CONFIG_PHY_GIGE
+#endif
+
+#define CONFIG_DRIVER_TI_CPSW
 #define CONFIG_PHYLIB
 
 #define CONFIG_SPL_ENV_SUPPORT
 #define CONFIG_SPL_NET_VCI_STRING	"AM43xx U-Boot SPL"
 
-#define CONFIG_SPL_ETH_SUPPORT
+#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_ETH_SUPPORT)
+#undef CONFIG_ENV_IS_IN_FAT
+#define CONFIG_ENV_IS_NOWHERE
 #define CONFIG_SPL_NET_SUPPORT
+#endif
+
 #define CONFIG_SYS_RX_ETH_BUFFER	64
 
 /* NAND support */