backlight: lcd: Constify lcd_ops

'struct lcd_ops' passed in lcd_device_register() is not modified by core
backlight code, so it can be made const for code safety.  This allows
drivers to also define the structure as const.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20240424-video-backlight-lcd-ops-v2-1-1aaa82b07bc6@kernel.orgSigned-off-by: Lee Jones <lee@kernel.org>

drivers/video/backlight/lcd.c

@@ -188,7 +188,7 @@ ATTRIBUTE_GROUPS(lcd_device);
  * or a pointer to the newly allocated device.
  */
 struct lcd_device *lcd_device_register(const char *name, struct device *parent,
-		void *devdata, struct lcd_ops *ops)
+		void *devdata, const struct lcd_ops *ops)
 {
 	struct lcd_device *new_ld;
 	int rc;
@@ -276,7 +276,7 @@ static int devm_lcd_device_match(struct device *dev, void *res, void *data)
  */
 struct lcd_device *devm_lcd_device_register(struct device *dev,
 		const char *name, struct device *parent,
-		void *devdata, struct lcd_ops *ops)
+		void *devdata, const struct lcd_ops *ops)
 {
 	struct lcd_device **ptr, *lcd;
 

include/linux/lcd.h

@@ -61,7 +61,7 @@ struct lcd_device {
 	   points to something in the body of that driver, it is also invalid. */
 	struct mutex ops_lock;
 	/* If this is NULL, the backing module is unloaded */
-	struct lcd_ops *ops;
+	const struct lcd_ops *ops;
 	/* Serialise access to set_power method */
 	struct mutex update_lock;
 	/* The framebuffer notifier block */
@@ -102,10 +102,10 @@ static inline void lcd_set_power(struct lcd_device *ld, int power)
 }
 
 extern struct lcd_device *lcd_device_register(const char *name,
-	struct device *parent, void *devdata, struct lcd_ops *ops);
+	struct device *parent, void *devdata, const struct lcd_ops *ops);
 extern struct lcd_device *devm_lcd_device_register(struct device *dev,
 	const char *name, struct device *parent,
-	void *devdata, struct lcd_ops *ops);
+	void *devdata, const struct lcd_ops *ops);
 extern void lcd_device_unregister(struct lcd_device *ld);
 extern void devm_lcd_device_unregister(struct device *dev,
 	struct lcd_device *ld);