imx6: enable early spi environment access on aristainetos boards

On aristianetos boards the display type is detected
through "panel" environment variable. Dependend on the
display type we detect the board type and this decides which
DTB we have to use for the board.

So we need early spi environment access.

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/configs/aristainetos2bcsl_defconfig b/configs/aristainetos2bcsl_defconfig
index 8e6d299..3013962 100644
--- a/configs/aristainetos2bcsl_defconfig
+++ b/configs/aristainetos2bcsl_defconfig
@@ -56,6 +56,7 @@
 CONFIG_MULTI_DTB_FIT=y
 CONFIG_ENV_OVERWRITE=y
 CONFIG_ENV_IS_IN_SPI_FLASH=y
+CONFIG_ENV_SPI_EARLY=y
 CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_VERSION_VARIABLE=y