of: Move testcase FDT data into drivers/of

The testcase data is usable by any platform. This patch moves it into
the drivers/of directory so it can be included by any architecture.

Using the test cases requires manually adding #include <testcases.dtsi>
to the end of the boards .dtsi file and enabling CONFIG_OF_SELFTEST. Not
pretty though. A useful project would be to make the testcase code
easier to execute.

Signed-off-by: Grant Likely <grant.likely@linaro.org>

scripts/Makefile.lib

@@ -152,6 +152,7 @@ ld_flags       = $(LDFLAGS) $(ldflags-y)
 dtc_cpp_flags  = -Wp,-MD,$(depfile).pre.tmp -nostdinc                    \
 		 -I$(srctree)/arch/$(SRCARCH)/boot/dts                   \
 		 -I$(srctree)/arch/$(SRCARCH)/boot/dts/include           \
+		 -I$(srctree)/drivers/of/testcase-data                   \
 		 -undef -D__DTS__
 
 # Finds the multi-part object the current object will be linked into