dts: move device tree sources to arch/$(ARCH)/dts/

Unlike Linux Kernel, U-Boot historically had *.dts files under
board/$(VENDOR)/dts/ and *.dtsi files under arch/$(ARCH)/dts/.

I think arch/$(ARCH)/dts dicretory is a better location
to store both *.dts and *.dtsi files.

For example, before this commit, board/xilinx/dts directory
had both Microblaze dts (microblaze-generic.dts) and
ARM dts (zynq-*.dts), which are totally unrelated.

This commit moves *.dts to arch/$(ARCH)/dts/ directories,
allowing us to describe nicely mutiple DTBs generation in the next commit.
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>

dts/Makefile

@@ -12,9 +12,9 @@ ifeq ($(DEVICE_TREE),)
 DEVICE_TREE := notfound
 endif
 
-DTS := $(srctree)/board/$(VENDOR)/dts/$(DEVICE_TREE).dts
+DTS := $(srctree)/arch/$(ARCH)/dts/$(DEVICE_TREE).dts
 
-DTC_FLAGS += -i $(srctree)/arch/$(ARCH)/dts -R 4 -p 0x1000
+DTC_FLAGS += -R 4 -p 0x1000
 
 $(obj)/dt.dtb: $(DTS) FORCE
 	$(call if_changed_dep,dtc)

scripts/Makefile.lib

@@ -153,7 +153,6 @@ ld_flags       = $(LDFLAGS) $(ldflags-y)
 
 # Modified for U-Boot
 dtc_cpp_flags  = -Wp,-MD,$(depfile).pre.tmp -nostdinc                    \
-		 -I$(srctree)/board/$(VENDOR)/dts/                       \
 		 -I$(srctree)/arch/$(ARCH)/dts                           \
 		 -undef -D__DTS__