fdt: Drop CONFIG_BINMAN_STANDALONE_FDT

This was added as a hack to work around not having an in-tree devicetree.
Now that this is fixed it is not needed.

Drop it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index 2badd26..633e038 100644
--- a/Makefile
+++ b/Makefile
@@ -945,7 +945,6 @@
 endif
 INPUTS-$(CONFIG_TPL) += tpl/u-boot-tpl.bin
 INPUTS-$(CONFIG_OF_SEPARATE) += u-boot.dtb
-INPUTS-$(CONFIG_BINMAN_STANDALONE_FDT) += u-boot.dtb
 ifeq ($(CONFIG_SPL_FRAMEWORK),y)
 INPUTS-$(CONFIG_OF_SEPARATE) += u-boot-dtb.img
 endif
@@ -1415,7 +1414,7 @@
 
 u-boot-dtb.img u-boot.img u-boot.kwb u-boot.pbl u-boot-ivt.img: \
 		$(if $(CONFIG_SPL_LOAD_FIT),u-boot-nodtb.bin \
-			$(if $(CONFIG_OF_SEPARATE)$(CONFIG_OF_EMBED)$(CONFIG_SANDBOX)$(CONFIG_BINMAN_STANDALONE_FDT),dts/dt.dtb) \
+			$(if $(CONFIG_OF_SEPARATE)$(CONFIG_OF_EMBED)$(CONFIG_SANDBOX),dts/dt.dtb) \
 		,$(UBOOT_BIN)) FORCE
 	$(call if_changed,mkimage)
 	$(BOARD_SIZE_CHECK)