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>

drivers/of/base.c

@@ -610,8 +610,9 @@ EXPORT_SYMBOL(of_find_node_by_phandle);
  *
  * The out_value is modified only if a valid u32 value can be decoded.
  */
-int of_property_read_u32_array(const struct device_node *np, char *propname,
-			       u32 *out_values, size_t sz)
+int of_property_read_u32_array(const struct device_node *np,
+			       const char *propname, u32 *out_values,
+			       size_t sz)
 {
 	struct property *prop = of_find_property(np, propname, NULL);
 	const __be32 *val;
@@ -645,7 +646,7 @@ EXPORT_SYMBOL_GPL(of_property_read_u32_array);
  *
  * The out_string pointer is modified only if a valid string can be decoded.
  */
-int of_property_read_string(struct device_node *np, char *propname,
+int of_property_read_string(struct device_node *np, const char *propname,
 				const char **out_string)
 {
 	struct property *prop = of_find_property(np, propname, NULL);

include/linux/of.h

@@ -196,12 +196,13 @@ extern struct property *of_find_property(const struct device_node *np,
 					 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 bool of_have_populated_dt(void)
 }
 
 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 @@ static inline int of_property_read_string(struct device_node *np,
 #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);