kernel-doc: move kernel-doc tools to scripts/

tools/kernel-doc/docproc.c and tools/kernel-doc/kernel-doc are
files imported from Linux Kernel.

They originally resided under scripts/ directory in Linux Kernel.

This commit moves them to the original location.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index a3979ec..75fd7f3 100644
--- a/Makefile
+++ b/Makefile
@@ -1149,9 +1149,6 @@
 env: depend scripts_basic
 	$(Q)$(MAKE) $(build)=tools/$@
 
-xmldocs pdfdocs psdocs htmldocs mandocs: tools/kernel-doc/docproc
-	$(Q)$(MAKE) U_BOOT_VERSION=$(U_BOOT_VERSION) $(build)=doc/DocBook $@
-
 tools-all: HOST_TOOLS_ALL=y
 tools-all: env tools ;
 
@@ -1259,6 +1256,13 @@
 	F=`basename $(TOPDIR)` ; cd .. ; \
 	gtar --force-local -zcvf `LC_ALL=C date "+$$F-%Y-%m-%d-%T.tar.gz"` $$F
 
+
+# Documentation targets
+# ---------------------------------------------------------------------------
+%docs: scripts_basic FORCE
+	$(Q)$(MAKE) $(build)=scripts build_docproc
+	$(Q)$(MAKE) $(build)=doc/DocBook $@
+
 # Dummies...
 PHONY += prepare scripts
 prepare: ;