Fix bug in sha256 verify

It was using twice as large data block as it should have been,
causing verify failures.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/verify.c b/verify.c
index 59f1ddf..c894b60 100644
--- a/verify.c
+++ b/verify.c
@@ -212,7 +212,7 @@
 {
 	void *p = io_u_verify_off(hdr, io_u, header_num);
 	struct vhdr_sha256 *vh = hdr_priv(hdr);
-	uint8_t sha256[128];
+	uint8_t sha256[64];
 	struct sha256_ctx sha256_ctx = {
 		.buf = sha256,
 	};
diff --git a/verify.h b/verify.h
index c12bc7d..be98c54 100644
--- a/verify.h
+++ b/verify.h
@@ -37,7 +37,7 @@
 	uint8_t sha512[128];
 };
 struct vhdr_sha256 {
-	uint8_t sha256[128];
+	uint8_t sha256[64];
 };
 struct vhdr_sha1 {
 	uint32_t sha1[5];