dt: add empty of_get_property for non-dt

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

This also fixes the current Tegra compile problem in linux-next.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

include/linux/of.h

@@ -256,6 +256,13 @@ static inline int of_property_read_string(struct device_node *np,
 	return -ENOSYS;
 }
 
+static inline const void *of_get_property(const struct device_node *node,
+				const char *name,
+				int *lenp)
+{
+	return NULL;
+}
+
 #endif /* CONFIG_OF */
 
 static inline int of_property_read_u32(const struct device_node *np,