spl: make CONFIG_OF_EMBED pass dts through fdtgrep

Building spl with CONFIG_OF_EMBED enabled results in an error message
on my board: "SPL image too big". This is because the fdtgrep build
step is only executed for CONFIG_OF_SEPARATE.

Fix this by moving the fdtgrep build step ('cmd_fdtgreo') from
scripts/Makefile.spl to dts/Makefile so that the reduced dtb is
available for all kinds of spl builds.

The resulting variable name for the embedded device tree blob changes,
too, which is why common.h and fdtdec.c have tiny changes.

Signed-off-by: Simon Goldschmidt <sgoldschmidt@de.pepperl-fuchs.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/scripts/Makefile.spl b/scripts/Makefile.spl
index b5e7019..64390e5 100644
--- a/scripts/Makefile.spl
+++ b/scripts/Makefile.spl
@@ -239,24 +239,8 @@
 	@bss_size_str=$(shell $(NM) $< | awk 'BEGIN {size = 0} /__bss_size/ {size = $$1} END {print "ibase=16; " toupper(size)}' | bc); \
 	dd if=/dev/zero of=$@ bs=1 count=$${bss_size_str} 2>/dev/null;
 
-# Pass the original device tree file through fdtgrep twice. The first pass
-# removes any unwanted nodes (i.e. those which don't have the
-# 'u-boot,dm-pre-reloc' property and thus are not needed by SPL. The second
-# pass removes various unused properties from the remaining nodes.
-# The output is typically a much smaller device tree file.
-ifeq ($(CONFIG_TPL_BUILD),y)
-fdtgrep_props := -b u-boot,dm-pre-reloc -b u-boot,dm-tpl
-else
-fdtgrep_props := -b u-boot,dm-pre-reloc -b u-boot,dm-spl
-endif
-quiet_cmd_fdtgrep = FDTGREP $@
-      cmd_fdtgrep = $(objtree)/tools/fdtgrep $(fdtgrep_props) -RT $< \
-		-n /chosen -n /config -O dtb | \
-	$(objtree)/tools/fdtgrep -r -O dtb - -o $@ \
-		$(addprefix -P ,$(subst $\",,$(CONFIG_OF_SPL_REMOVE_PROPS)))
-
-$(obj)/$(SPL_BIN).dtb: dts/dt.dtb $(objtree)/tools/fdtgrep FORCE
-	$(call if_changed,fdtgrep)
+$(obj)/$(SPL_BIN).dtb: dts/dt-spl.dtb FORCE
+	$(call if_changed,copy)
 
 pythonpath = PYTHONPATH=scripts/dtc/pylibfdt