Enable ROCKCHIP_SPL_BACK_TO_BROM for rock2 board

Rock2 has been tested with back to brom feature. The tricky part is that
with this feature the default environment is inside u-boot, and it's
defined for every rk3288 board independetly. So I just changed it for
rock2 here if ROCKCHIP_SPL_BACK_TO_BROM.

Solve by moving environment after u-boot before 1M boundary

Signed-off-by: Sandy Patterson <apatterson@sightlogix.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/rock2_defconfig b/configs/rock2_defconfig
index fc9ff78..0361256 100644
--- a/configs/rock2_defconfig
+++ b/configs/rock2_defconfig
@@ -7,6 +7,8 @@
 CONFIG_DEFAULT_DEVICE_TREE="rk3288-rock2-square"
 CONFIG_SPL_STACK_R=y
 CONFIG_SPL_STACK_R_MALLOC_SIMPLE_LEN=0x2000
+# CONFIG_SPL_MMC_SUPPORT is not set
+CONFIG_ROCKCHIP_SPL_BACK_TO_BROM=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_BOOTZ=y
 # CONFIG_CMD_IMLS is not set