Convert CONFIG_SYS_CONSOLE_ENV_OVERWRITE to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_CONSOLE_ENV_OVERWRITE

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/socfpga_de0_nano_soc_defconfig b/configs/socfpga_de0_nano_soc_defconfig
index 402d9fb..140ac4d 100644
--- a/configs/socfpga_de0_nano_soc_defconfig
+++ b/configs/socfpga_de0_nano_soc_defconfig
@@ -6,6 +6,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="socfpga_cyclone5_de0_nano_soc"
 CONFIG_FIT=y
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
+CONFIG_SYS_CONSOLE_ENV_OVERWRITE=y
 CONFIG_VERSION_VARIABLE=y
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_SPL=y