TESTS: read12/read16 change signature to return an optional task structure

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>

test-tool/test_read12_rdprotect.c

@@ -41,7 +41,7 @@ test_read12_rdprotect(void)
 	if (!inq->protect || (rc16 != NULL && !rc16->prot_en)) {
 		logging(LOG_VERBOSE, "Device does not support/use protection information. All commands should fail.");
 		for (i = 1; i < 8; i++) {
-			ret = read12(sd, 0,
+			ret = read12(sd, NULL, 0,
 				     block_size, block_size,
 				     i, 0, 0, 0, 0, NULL,
 				     EXPECT_INVALID_FIELD_IN_CDB);