of.h: Improve of_match_node()

Suppress the following compiler warning if CONFIG_OF=n:

> drivers/scsi/ufs-drivers/ufs-hisi.c:560:34: warning: unused variable 'ufs_hisi_of_match' [-Wunused-const-variable]

Signed-off-by: Bart Van Assche <bvanassche@acm.org>

include/linux/of.h

@@ -854,8 +854,14 @@ static inline phys_addr_t of_dma_get_max_cpu_address(struct device_node *np)
 	return PHYS_ADDR_MAX;
 }
 
-#define of_match_ptr(_ptr)	NULL
-#define of_match_node(_matches, _node)	NULL
+#define of_match_ptr(_ptr) ((_ptr), NULL)
+
+static inline const struct of_device_id *
+of_match_node(const struct of_device_id *matches,
+	      const struct device_node *node)
+{
+	return NULL;
+}
 #endif /* CONFIG_OF */
 
 /* Default string compare functions, Allow arch asm/prom.h to override */