params: Replace zero-length array with flexible-array member

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://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arraysSigned-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

kernel/params.c

@@ -530,7 +530,7 @@ struct module_param_attrs
 {
 	unsigned int num;
 	struct attribute_group grp;
-	struct param_attribute attrs[0];
+	struct param_attribute attrs[];
 };
 
 #ifdef CONFIG_SYSFS