of/irq: add empty irq_of_parse_and_map() for non-dt builds

Add a empty irq_of_parse_and_map() function that returns 0 for non-dt
builds and avoid having #ifdef CONFIG_OF around all calls to
irq_of_parse_and_map(). In addition to that, the irq_of_parse_and_map()
function declaration is made available only if CONFIG_OF_IRQ is defined,
which is the same config option that makes the irq_of_parse_and_map()
function definition available. While at it, fix a typo as well.

Changes since v1:
- Moved irq_of_parse_and_map() function declaration under CONFIG_OF_IRQ.
- Fix a minor typo in comments.

Suggested-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
[grant.likely: fix bug causing SPARC to break]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

include/linux/of_irq.h

@@ -11,7 +11,7 @@ struct of_irq;
 #include <linux/of.h>
 
 /*
- * irq_of_parse_and_map() is used ba all OF enabled platforms; but SPARC
+ * irq_of_parse_and_map() is used by all OF enabled platforms; but SPARC
  * implements it differently.  However, the prototype is the same for all,
  * so declare it here regardless of the CONFIG_OF_IRQ setting.
  */
@@ -76,5 +76,13 @@ extern struct device_node *of_irq_find_parent(struct device_node *child);
 extern void of_irq_init(const struct of_device_id *matches);
 
 #endif /* CONFIG_OF_IRQ */
-#endif /* CONFIG_OF */
+
+#else /* !CONFIG_OF */
+static inline unsigned int irq_of_parse_and_map(struct device_node *dev,
+						int index)
+{
+	return 0;
+}
+#endif /* !CONFIG_OF */
+
 #endif /* __OF_IRQ_H */