configs: ls1012a/ls1046a: Add CONFIG_ENV_OVERWRITE in defconfig

CONFIG_ENV_OVERWRITE disables write protection on various environment
variables like "ethaddr" and "serial".

Enable this config in LS1046A and LS1012A defconfigs. This resolves an
error while setting multiple values of "ethaddr" variable.

Before the change:
=> setenv ethaddr 00:E0:0C:00:06:0
=> setenv ethaddr 00:E0:0C:00:06:1
Error: Can't overwrite "ethaddr"
Error inserting "ethaddr" variable, errno=1

After the change:
=> setenv ethaddr 00:E0:0C:00:06:0
=> setenv ethaddr 00:E0:0C:00:06:1

Signed-off-by: Kuldeep Singh <kuldeep.singh@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/configs/ls1046aqds_sdcard_ifc_defconfig b/configs/ls1046aqds_sdcard_ifc_defconfig
index e17353e..959b8ff 100644
--- a/configs/ls1046aqds_sdcard_ifc_defconfig
+++ b/configs/ls1046aqds_sdcard_ifc_defconfig
@@ -51,6 +51,7 @@
 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:4m(nand_uboot),36m(nand_kernel),472m(nand_free);spi0.0:2m(uboot),14m(free)"
 # CONFIG_SPL_EFI_PARTITION is not set
 CONFIG_OF_CONTROL=y
+CONFIG_ENV_OVERWRITE=y
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_DM=y