kexec: 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/21Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

include/linux/kexec.h

@@ -208,7 +208,7 @@ struct crash_mem_range {
 struct crash_mem {
 	unsigned int max_nr_ranges;
 	unsigned int nr_ranges;
-	struct crash_mem_range ranges[0];
+	struct crash_mem_range ranges[];
 };
 
 extern int crash_exclude_mem_range(struct crash_mem *mem,