treewide: Replace zero-length arrays with flexible-array members

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].

This code was transformed with the help of Coccinelle:
(next-20220214$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)

@@
identifier S, member, array;
type T1, T2;
@@

struct S {
  ...
  T1 member;
  T2 array[
- 0
  ];
};

UAPI and wireless changes were intentionally excluded from this patch
and will be sent out separately.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

include/asm-generic/tlb.h

@@ -180,7 +180,7 @@ struct mmu_table_batch {
 	struct rcu_head		rcu;
 #endif
 	unsigned int		nr;
-	void			*tables[0];
+	void			*tables[];
 };
 
 #define MAX_TABLE_BATCH		\
@@ -227,7 +227,7 @@ struct mmu_gather_batch {
 	struct mmu_gather_batch	*next;
 	unsigned int		nr;
 	unsigned int		max;
-	struct page		*pages[0];
+	struct page		*pages[];
 };
 
 #define MAX_GATHER_BATCH	\