ARM: uniphier: drop fdt_file from CONFIG_EXTRA_ENV_SETTINGS

Now this environment is run-time set to the DTB name U-Boot is really
running with.  Drop the static define.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

include/configs/uniphier.h

@@ -193,7 +193,6 @@
 	"fdt_addr=0x00100000\0" \
 	"fdt_addr_r=0x84100000\0" \
 	"fdt_size=0x00008000\0" \
-	"fdt_file=" CONFIG_DEFAULT_DEVICE_TREE ".dtb\0" \
 	"kernel_addr=0x00200000\0" \
 	"kernel_addr_r=0x84200000\0" \
 	"kernel_size=0x00800000\0" \