iommufd/selftest: Fix ioctl return value in _test_cmd_trigger_vevents()

The ioctl returns 0 upon success, so !0 returning -1 breaks the selftest.

Drop the '!' to fix it.

Fixes: 1d235d8494 ("iommu/selftest: prevent use of uninitialized variable")
Link: https://patch.msgid.link/r/20251014214847.1113759-1-nicolinc@nvidia.com
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

tools/testing/selftests/iommu/iommufd_utils.h

@@ -1044,8 +1044,8 @@ static int _test_cmd_trigger_vevents(int fd, __u32 dev_id, __u32 nvevents)
 	};
 
 	while (nvevents--) {
-		if (!ioctl(fd, _IOMMU_TEST_CMD(IOMMU_TEST_OP_TRIGGER_VEVENT),
-			    &trigger_vevent_cmd))
+		if (ioctl(fd, _IOMMU_TEST_CMD(IOMMU_TEST_OP_TRIGGER_VEVENT),
+			  &trigger_vevent_cmd))
 			return -1;
 	}
 	return 0;