of/address: sparc: Declare of_iomap as an extern function for sparc again

This bug-fix makes sure that of_iomap is defined extern for sparc so that the
sparc-specific implementation of_iomap is once again used when including
include/linux/of_address.h in a sparc context. OF_GPIO that is now available for
sparc relies on this.

The bug was inadvertently introduced in a850a755, "of/address: add empty static
inlines for !CONFIG_OF", that added a static dummy inline for of_iomap when
!CONFIG_OF_ADDRESS. However, CONFIG_OF_ADDRESS is never defined for sparc, but
there is a sparc-specific implementation /arch/sparc/kernel/of_device_common.c.

This fix takes the same approach as 0bce04be that solved the equivalent problem
for of_address_to_resource.
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Acked-by: David Miller <davem@davemloft.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

arch/sparc/include/asm/prom.h

@@ -63,10 +63,13 @@ extern char *of_console_options;
 extern void irq_trans_init(struct device_node *dp);
 extern char *build_path_component(struct device_node *dp);
 
-/* SPARC has a local implementation */
+/* SPARC has local implementations */
 extern int of_address_to_resource(struct device_node *dev, int index,
 				  struct resource *r);
 #define of_address_to_resource of_address_to_resource
 
+void __iomem *of_iomap(struct device_node *node, int index);
+#define of_iomap of_iomap
+
 #endif /* __KERNEL__ */
 #endif /* _SPARC_PROM_H */

include/linux/of_address.h

@@ -42,10 +42,12 @@ static inline struct device_node *of_find_matching_node_by_address(
 {
 	return NULL;
 }
+#ifndef of_iomap
 static inline void __iomem *of_iomap(struct device_node *device, int index)
 {
 	return NULL;
 }
+#endif
 static inline const __be32 *of_get_address(struct device_node *dev, int index,
 					u64 *size, unsigned int *flags)
 {