OF: add empty of_device_is_available for !OF

Add an empty version of of_device_is_available.

Signed-off-by: Rob Herring <[e-mail]>

include/linux/of.h

···
 	return 0;
 }
 
+static inline int of_device_is_available(const struct device_node *device)
+{
+	return 0;
+}
+
 static inline struct property *of_find_property(const struct device_node *np,
 						const char *name,
 						int *lenp)