crypto: lib/blake2s - reduce stack frame usage in self test

Using 3 blocks here doesn't give us much more than using 2, and it
causes a stack frame size warning on certain compiler/config/arch
combinations:

lib/crypto/blake2s-selftest.c: In function 'blake2s_selftest':
>> lib/crypto/blake2s-selftest.c:632:1: warning: the frame size of 1088 bytes is larger than 1024 bytes [-Wframe-larger-than=]
632 | }
| ^

So this patch just reduces the block from 3 to 2, which makes the
warning go away.

Reported-by: kernel test robot <[e-mail]>
Link: https://lore.kernel.org/linux-crypto/[e-mail]
Fixes: 2d16803c562e ("crypto: blake2s - remove shash module")
Signed-off-by: Jason A. Donenfeld <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

lib/crypto/blake2s-selftest.c

···
 		enum { TEST_ALIGNMENT = 16 };
 		u8 unaligned_block[BLAKE2S_BLOCK_SIZE + TEST_ALIGNMENT - 1]
 					__aligned(TEST_ALIGNMENT);
-		u8 blocks[BLAKE2S_BLOCK_SIZE * 3];
+		u8 blocks[BLAKE2S_BLOCK_SIZE * 2];
 		struct blake2s_state state1, state2;
 
 		get_random_bytes(blocks, sizeof(blocks));
···
     defined(CONFIG_CRYPTO_ARCH_HAVE_LIB_BLAKE2S)
 		memcpy(&state1, &state, sizeof(state1));
 		memcpy(&state2, &state, sizeof(state2));
-		blake2s_compress(&state1, blocks, 3, BLAKE2S_BLOCK_SIZE);
-		blake2s_compress_generic(&state2, blocks, 3, BLAKE2S_BLOCK_SIZE);
+		blake2s_compress(&state1, blocks, 2, BLAKE2S_BLOCK_SIZE);
+		blake2s_compress_generic(&state2, blocks, 2, BLAKE2S_BLOCK_SIZE);
 		if (memcmp(&state1, &state2, sizeof(state1))) {
 			pr_err("blake2s random compress self-test %d: FAIL\n",
 			       i + 1);