crypto: lib/aesgcm - Reduce stack usage in libaesgcm_init

The stack frame in libaesgcm_init triggers a size warning on x86-64.
Reduce it by making buf static.

Signed-off-by: Herbert Xu <[e-mail]>
Acked-by: Ard Biesheuvel <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

lib/crypto/aesgcm.c

···
 		u8 tagbuf[AES_BLOCK_SIZE];
 		int plen = aesgcm_tv[i].plen;
 		struct aesgcm_ctx ctx;
-		u8 buf[sizeof(ptext12)];
+		static u8 buf[sizeof(ptext12)];
 
 		if (aesgcm_expandkey(&ctx, aesgcm_tv[i].key, aesgcm_tv[i].klen,
 				     aesgcm_tv[i].clen - plen)) {