Prefer VERIFY0P(n) over VERIFY3P(n, ==, NULL)

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/
Closes #17591

cmd/zfs/zfs_main.c

@@ -923,7 +923,7 @@ zfs_do_clone(int argc, char **argv)
 	return (!!ret);
 
 usage:
-	ASSERT3P(zhp, ==, NULL);
+	ASSERT0P(zhp);
 	nvlist_free(props);
 	usage(B_FALSE);
 	return (-1);