net: Move CONFIG_E1000 options to Kconfig

Move config for the E1000 Ethernet driver to Kconfig and tidy up affected
boards.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/configs/gwventana_defconfig b/configs/gwventana_defconfig
index d81f941..e294cac 100644
--- a/configs/gwventana_defconfig
+++ b/configs/gwventana_defconfig
@@ -7,5 +7,7 @@
 # CONFIG_CMD_IMLS is not set
 # CONFIG_CMD_FLASH is not set
 CONFIG_DM=y
+CONFIG_NETDEVICES=y
+CONFIG_E1000=y
 CONFIG_DM_SERIAL=y
 CONFIG_SYS_PROMPT="Ventana > "