Convert CONFIG_ENV_OVERWRITE to Kconfig

This converts the following to Kconfig:
   CONFIG_ENV_OVERWRITE

Signed-off-by: Adam Ford <aford173@gmail.com>
[trini: Rerun migration, remove some comments]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/ls1043aqds_defconfig b/configs/ls1043aqds_defconfig
index e67f3d0..57cf141 100644
--- a/configs/ls1043aqds_defconfig
+++ b/configs/ls1043aqds_defconfig
@@ -32,6 +32,7 @@
 CONFIG_MP=y
 CONFIG_MTDPARTS_DEFAULT="mtdparts=60000000.nor:2m@0x100000(nor_bank0_uboot),40m@0x1100000(nor_bank0_fit),7m(nor_bank0_user),2m@0x4100000(nor_bank4_uboot),40m@0x5100000(nor_bank4_fit),-(nor_bank4_user);7e800000.flash:1m(nand_uboot),1m(nand_uboot_env),20m(nand_fit);spi0.0:1m(uboot),5m(kernel),1m(dtb),9m(file_system)"
 CONFIG_OF_CONTROL=y
+CONFIG_ENV_OVERWRITE=y
 CONFIG_ENV_IS_IN_FLASH=y
 CONFIG_ENV_ADDR=0x60300000
 CONFIG_DM=y