Makefile: add coccicheck target

Coccinelle is a program for static code analysis.
For details on Coccinelle see

	http://coccinelle.lip6.fr/

Add scripts/coccicheck copied from Linux kernel v4.14.

The coccicheck script executes the tests *.cocci in
directory scripts/coccinelle by calling spatch.

In Makefile add a coccicheck target. You can use it with

	make coccicheck MODE=<mode>

	where mode in patch, report, context, org.

Add a copy of Linux v4.14 file Documentation/dev-tools/coccinelle.rst
as doc/README.coccinelle.

Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/Makefile b/Makefile
index b5f81e3..fea1954 100644
--- a/Makefile
+++ b/Makefile
@@ -1572,6 +1572,7 @@
 	@echo  ''
 	@echo  'Static analysers'
 	@echo  '  checkstack      - Generate a list of stack hogs'
+	@echo  '  coccicheck      - Execute static code analysis with Coccinelle'
 	@echo  ''
 	@echo  'Documentation targets:'
 	@$(MAKE) -f $(srctree)/doc/DocBook/Makefile dochelp
@@ -1664,6 +1665,14 @@
 	$(build)=$(build-dir) $(@:.ko=.o)
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
 
+# Consistency checks
+# ---------------------------------------------------------------------------
+
+PHONY += coccicheck
+
+coccicheck:
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/$@
+
 # FIXME Should go into a make.lib or something
 # ===========================================================================