w1: Constify struct w1_family_ops

The fops field in the w1_family struct is never modified. Make it const
to indicate that. Constifying the pointer makes it possible for drivers
to declare static w1_family_ops structs const, which in turn will allow
the compiler to put it in read-only memory.
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Link: https://lore.kernel.org/r/20201004193202.4044-2-rikard.falkeborn@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/w1/w1.c

@@ -613,7 +613,7 @@ static int w1_uevent(struct device *dev, struct kobj_uevent_env *env)
 
 static int w1_family_notify(unsigned long action, struct w1_slave *sl)
 {
-	struct w1_family_ops *fops;
+	const struct w1_family_ops *fops;
 	int err;
 
 	fops = sl->family->fops;

include/linux/w1.h

@@ -269,7 +269,7 @@ struct w1_family {
 	struct list_head	family_entry;
 	u8			fid;
 
-	struct w1_family_ops	*fops;
+	const struct w1_family_ops *fops;
 
 	const struct of_device_id *of_match_table;