net: Move the CMD_NET config to defconfigs

This also selects CONFIG_NET for any CONFIG_CMD_NET board.

Remove the imx default for CONFIG_NET.

This moves the config that was defined by 60296a8 (commands: add more
command entries in Kconfig).

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/configs/odroid_defconfig b/configs/odroid_defconfig
index af8cb7a..5efcdf5 100644
--- a/configs/odroid_defconfig
+++ b/configs/odroid_defconfig
@@ -4,6 +4,7 @@
 # CONFIG_SYS_MALLOC_CLEAR_ON_INIT is not set
 CONFIG_DEFAULT_DEVICE_TREE="exynos4412-odroid"
 CONFIG_CMD_SETEXPR=y
+CONFIG_CMD_NET=y
 CONFIG_CMD_PMIC=y
 CONFIG_CMD_REGULATOR=y
 CONFIG_OF_CONTROL=y