arm: socfpga: DE1 use environment in common header

This removes the default environment from the de1 headers
and instead uses the common environment provided in
socfpga_common.h which now uses distro boot.

This board does not have a devicetree in the upstream kernel
source so set devicetree to socfpga_cyclone5_de1_soc.dtb.

Signed-off-by: Dalon Westergreen <dwesterg@gmail.com>
Acked-by: Marek Vasut <marex@denx.de>

--
Changes in V2:
 - Remove unneeded CONFIG_BOOTFILE
 - set devicetree name to match socfpga_{fpga model}_{board model}.dts
   pattern
diff --git a/configs/socfpga_de1_soc_defconfig b/configs/socfpga_de1_soc_defconfig
index 135dfac..211ea41 100644
--- a/configs/socfpga_de1_soc_defconfig
+++ b/configs/socfpga_de1_soc_defconfig
@@ -5,6 +5,7 @@
 CONFIG_TARGET_SOCFPGA_TERASIC_DE1_SOC=y
 CONFIG_SPL_STACK_R_ADDR=0x00800000
 CONFIG_DEFAULT_DEVICE_TREE="socfpga_cyclone5_de1_soc"
+CONFIG_DEFAULT_FDT_FILE="socfpga_cyclone5_de1_soc.dtb"
 CONFIG_FIT=y
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE=y