dt: add empty of_machine_is_compatible

The patch adds an empty function for non-dt build, so that
drivers migrating to dt can save some '#ifdef CONFIG_OF'.

v3: New patch

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/include/linux/of.h b/include/linux/of.h
index 4386c5f..0e89aa0 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -326,6 +326,11 @@
 	return -ENOSYS;
 }
 
+static inline int of_machine_is_compatible(const char *compat)
+{
+	return 0;
+}
+
 #define of_match_ptr(_ptr)	NULL
 #define of_match_node(_matches, _node)	NULL
 #endif /* CONFIG_OF */