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/ls1021atwr_nor_lpuart_defconfig b/configs/ls1021atwr_nor_lpuart_defconfig
index 8f34613..d7afca9 100644
--- a/configs/ls1021atwr_nor_lpuart_defconfig
+++ b/configs/ls1021atwr_nor_lpuart_defconfig
@@ -2,3 +2,5 @@
 CONFIG_TARGET_LS1021ATWR=y
 CONFIG_SYS_EXTRA_OPTIONS="LPUART"
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_NETDEVICES=y
+CONFIG_E1000=y