rockchip: rk3399-puma: Move ENV_OFFSET to end of SPI NOR.

Puma SoMs have a 4 MB SPI NOR flash.
Therefore we can move the environment to the end of the flash
(4 MiB - 16 kiB) in order to not overlap with SPL.

Reported-by: Jakob Unterwurzacher <jakob.unterwurzacher@theobroma-systems.com>
Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/board/theobroma-systems/puma_rk3399/Kconfig b/board/theobroma-systems/puma_rk3399/Kconfig
index 8a94cbd..9e23252 100644
--- a/board/theobroma-systems/puma_rk3399/Kconfig
+++ b/board/theobroma-systems/puma_rk3399/Kconfig
@@ -16,6 +16,6 @@
 	default 0x2000
 
 config ENV_OFFSET
-	default 0x3c000 if ENV_IS_IN_SPI_FLASH
+	default 0x3fc000 if ENV_IS_IN_SPI_FLASH
 
 endif