arm: socfpga: DE0 use environment in common header

This removes the default environment from the de0 headers
and instead uses the common environment provided in
socfpga_common.h which now uses distro boot.

In addition to the above, add support to boot from the custom
a2 type partition

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

--
Changes in v2:
 - Remove unneeded CONFIG_BOOTFILE
diff --git a/configs/socfpga_de0_nano_soc_defconfig b/configs/socfpga_de0_nano_soc_defconfig
index af41e1e..b122135 100644
--- a/configs/socfpga_de0_nano_soc_defconfig
+++ b/configs/socfpga_de0_nano_soc_defconfig
@@ -4,6 +4,7 @@
 CONFIG_TARGET_SOCFPGA_TERASIC_DE0_NANO=y
 CONFIG_SPL_STACK_R_ADDR=0x00800000
 CONFIG_DEFAULT_DEVICE_TREE="socfpga_cyclone5_de0_nano_soc"
+CONFIG_DEFAULT_FDT_FILE="socfpga_cyclone5_de0_nano_soc.dtb"
 CONFIG_FIT=y
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE=y
@@ -58,3 +59,5 @@
 CONFIG_G_DNL_VENDOR_NUM=0x0525
 CONFIG_G_DNL_PRODUCT_NUM=0xa4a5
 CONFIG_USE_TINY_PRINTF=y
+CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION_TYPE=y
+CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION_TYPE=0xa2
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