docs: dt: update writing-schema.rst references

Changeset b83db5b84900 ("docs: dt: Group DT docs into relevant sub-sections")
renamed: Documentation/devicetree/writing-schema.rst
to: Documentation/devicetree/bindings/writing-schema.rst.

Update the cross-references accordingly.

Fixes: b83db5b84900 ("docs: dt: Group DT docs into relevant sub-sections")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/7cfddf303f1508d26f90d87546d3812faebfc5ba.1617279356.git.mchehab+huawei@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index df8b23d..3e8da40 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3152,7 +3152,7 @@
 		    ($line =~ /^new file mode\s*\d+\s*$/) &&
 		    ($realfile =~ m@^Documentation/devicetree/bindings/.*\.txt$@)) {
 			WARN("DT_SCHEMA_BINDING_PATCH",
-			     "DT bindings should be in DT schema format. See: Documentation/devicetree/writing-schema.rst\n");
+			     "DT bindings should be in DT schema format. See: Documentation/devicetree/bindings/writing-schema.rst\n");
 		}
 
 # Check for wrappage within a valid hunk of the file