of: constify property name parameters for helper functions

The helper functions for reading u32 integers, u32 arrays and strings
should have the property name as a const pointer.

Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/include/linux/of.h b/include/linux/of.h
index bd716f8..0085bb0 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -196,12 +196,13 @@
 					 const char *name,
 					 int *lenp);
 extern int of_property_read_u32_array(const struct device_node *np,
-				      char *propname,
+				      const char *propname,
 				      u32 *out_values,
 				      size_t sz);
 
-extern int of_property_read_string(struct device_node *np, char *propname,
-					const char **out_string);
+extern int of_property_read_string(struct device_node *np,
+				   const char *propname,
+				   const char **out_string);
 extern int of_device_is_compatible(const struct device_node *device,
 				   const char *);
 extern int of_device_is_available(const struct device_node *device);
@@ -242,13 +243,15 @@
 }
 
 static inline int of_property_read_u32_array(const struct device_node *np,
-				char *propname, u32 *out_values, size_t sz)
+					     const char *propname,
+					     u32 *out_values, size_t sz)
 {
 	return -ENOSYS;
 }
 
 static inline int of_property_read_string(struct device_node *np,
-				char *propname, const char **out_string)
+					  const char *propname,
+					  const char **out_string)
 {
 	return -ENOSYS;
 }
@@ -256,7 +259,7 @@
 #endif /* CONFIG_OF */
 
 static inline int of_property_read_u32(const struct device_node *np,
-				       char *propname,
+				       const char *propname,
 				       u32 *out_value)
 {
 	return of_property_read_u32_array(np, propname, out_value, 1);