crypto: talitos - Replace zero-length arrays with DECLARE_FLEX_ARRAY() helper

Zero-length arrays are deprecated and we are moving towards adopting
C99 flexible-array members, instead. So, replace zero-length arrays
declarations in anonymous union with the new DECLARE_FLEX_ARRAY()
helper macro.

This helper allows for flexible-array members in unions.

Link: https://github.com/KSPP/linux/issues/193
Link: https://github.com/KSPP/linux/issues/216
Link: https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/talitos.h

···
 	dma_addr_t dma_link_tbl;
 	struct talitos_desc desc;
 	union {
-		struct talitos_ptr link_tbl[0];
-		u8 buf[0];
+		DECLARE_FLEX_ARRAY(struct talitos_ptr, link_tbl);
+		DECLARE_FLEX_ARRAY(u8, buf);
 	};
 };