am335x_evm: enable networking in SPL

This patch adds support for networking in SPL on TI AM335x based
boards. Vendor Class Identifier used by SPL during BOOTP is
"AM335x U-Boot SPL".
Signed-off-by: NIlya Yanok <ilya.yanok@cogentembedded.com>

include/configs/am335x_evm.h

@@ -195,7 +195,7 @@
 #define CONFIG_SPL
 #define CONFIG_SPL_FRAMEWORK
 #define CONFIG_SPL_TEXT_BASE		0x402F0400
-#define CONFIG_SPL_MAX_SIZE		(46 * 1024)
+#define CONFIG_SPL_MAX_SIZE		(101 * 1024)
 #define CONFIG_SPL_STACK		CONFIG_SYS_INIT_SP_ADDR
 
 #define CONFIG_SPL_BSS_START_ADDR	0x80000000
@@ -215,6 +215,9 @@
 #define CONFIG_SPL_SERIAL_SUPPORT
 #define CONFIG_SPL_GPIO_SUPPORT
 #define CONFIG_SPL_YMODEM_SUPPORT
+#define CONFIG_SPL_NET_SUPPORT
+#define CONFIG_SPL_NET_VCI_STRING	"AM335x U-Boot SPL"
+#define CONFIG_SPL_ETH_SUPPORT
 #define CONFIG_SPL_LDSCRIPT		"$(CPUDIR)/omap-common/u-boot-spl.lds"
 
 /*