[SPARC]: constify some paramaters of OF routines

This starts bringing the PowerPC and Sparc implemetations back closer
together.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/asm-sparc/prom.h

@@ -85,12 +85,14 @@ extern struct device_node *of_find_node_by_phandle(phandle handle);
 extern struct device_node *of_get_parent(const struct device_node *node);
 extern struct device_node *of_get_next_child(const struct device_node *node,
 					     struct device_node *prev);
-extern struct property *of_find_property(struct device_node *np,
+extern struct property *of_find_property(const struct device_node *np,
 					 const char *name,
 					 int *lenp);
-extern int of_device_is_compatible(struct device_node *device, const char *);
-extern const void *of_get_property(struct device_node *node, const char *name,
-			     int *lenp);
+extern int of_device_is_compatible(const struct device_node *device,
+				   const char *);
+extern const void *of_get_property(const struct device_node *node,
+				   const char *name,
+				   int *lenp);
 #define get_property(node,name,lenp) of_get_property(node,name,lenp)
 extern int of_set_property(struct device_node *node, const char *name, void *val, int len);
 extern int of_getintprop_default(struct device_node *np,