devicetree: add helper inline for retrieving a node's full name

The pattern (np ? np->full_name : "<none>") is rather common in the
kernel, but can also make for quite long lines.  This patch adds a new
inline function, of_node_full_name() so that the test for a valid node
pointer doesn't need to be open coded at all call sites.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>

kernel/irq/irqdomain.c

@@ -448,7 +448,7 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
 	}
 
 	pr_debug("irq %lu on domain %s mapped to virtual irq %u\n",
-		hwirq, domain->of_node ? domain->of_node->full_name : "null", virq);
+		hwirq, of_node_full_name(domain->of_node), virq);
 
 	return virq;
 }
@@ -477,7 +477,7 @@ unsigned int irq_create_of_mapping(struct device_node *controller,
 			return intspec[0];
 #endif
 		pr_warning("no irq domain found for %s !\n",
-			   controller->full_name);
+			   of_node_full_name(controller));
 		return 0;
 	}
 
@@ -725,8 +725,8 @@ static int virq_debug_show(struct seq_file *m, void *private)
 			data = irq_desc_get_chip_data(desc);
 			seq_printf(m, data ? "0x%p  " : "  %p  ", data);
 
-			if (desc->irq_data.domain && desc->irq_data.domain->of_node)
-				p = desc->irq_data.domain->of_node->full_name;
+			if (desc->irq_data.domain)
+				p = of_node_full_name(desc->irq_data.domain->of_node);
 			else
 				p = none;
 			seq_printf(m, "%s\n", p);