Correct compilation errors reported by GCC 10/11

New `zfs_type_t` value `ZFS_TYPE_INVALID` is introduced.
Variable initialization is now possible to make GCC happy.

Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: szubersk <szuberskidamian@gmail.com>
Closes #12167
Closes #13103

lib/libzutil/os/linux/zutil_import_os.c

@@ -754,6 +754,9 @@ no_dev:
 
 	return (ret);
 #else
+	(void) path;
+	(void) ds;
+	(void) wholedisk;
 	return (ENOENT);
 #endif
 }