ARM: renesas: Consistently enable ENV_OVERWRITE on Renesas R-Car

Move CONFIG_ENV_OVERWRITE=y into commont renesas_rcar.config to make sure
this configuration option is consistently enabled on all of Renesas R-Car
Gen2, Gen3, Gen4. Currently this option is not enabled on Gen4, this fix
corrects that omission.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
diff --git a/configs/renesas_rcar.config b/configs/renesas_rcar.config
index 351803b..d0a12f2 100644
--- a/configs/renesas_rcar.config
+++ b/configs/renesas_rcar.config
@@ -17,6 +17,7 @@
 CONFIG_DM_REGULATOR_GPIO=y
 CONFIG_DM_SPI=y
 CONFIG_DM_SPI_FLASH=y
+CONFIG_ENV_OVERWRITE=y
 CONFIG_FIT=y
 CONFIG_HUSH_PARSER=y
 CONFIG_MTD=y