stm class: Replace zero-length array with flexible-array

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21

Signed-off-by: Gustavo A. R. Silva <[e-mail]>

drivers/hwtracing/stm/policy.c

···
 	unsigned int		first_channel;
 	unsigned int		last_channel;
 	/* this is the one that's exposed to the attributes */
-	unsigned char		priv[0];
+	unsigned char		priv[];
 };
 
 void *stp_policy_node_priv(struct stp_policy_node *pn)

drivers/hwtracing/stm/stm.h

···
 
 struct stp_master {
 	unsigned int	nr_free;
-	unsigned long	chan_map[0];
+	unsigned long	chan_map[];
 };
 
 struct stm_device {
···
 	const struct config_item_type		*pdrv_node_type;
 	/* master allocation */
 	spinlock_t		mc_lock;
-	struct stp_master	*masters[0];
+	struct stp_master	*masters[];
 };
 
 #define to_stm_device(_d)				\