kbuild: Do not append dtb for OF_EMBED case

dtb is already included in binary that's why there is no need to replace
u-boot-spl.bin with u-boot-spl-dtb.bin. This is only needed for
OF_SEPARATE is enabled. Only copy -nodtb.bin version which is straight
output from objcopy -O binary.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

scripts/Makefile.spl

@@ -165,7 +165,7 @@ cmd_cat = cat $(filter-out $(PHONY), $^) > $@
 quiet_cmd_copy = COPY    $@
       cmd_copy = cp $< $@
 
-ifeq ($(CONFIG_SPL_OF_CONTROL),y)
+ifeq ($(CONFIG_SPL_OF_CONTROL)$(CONFIG_OF_SEPARATE),yy)
 $(obj)/$(SPL_BIN)-dtb.bin: $(obj)/$(SPL_BIN)-nodtb.bin $(obj)/$(SPL_BIN)-pad.bin \
 		$(obj)/$(SPL_BIN).dtb FORCE
 	$(call if_changed,cat)