FreeBSD: Fix uninitialized pointer read in spa_import_rootpool()

The FreeBSD project's coverity scans found this.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #13923

module/os/freebsd/zfs/spa_os.c

@@ -250,7 +250,7 @@ spa_import_rootpool(const char *name, bool checkpointrewind)
 		mutex_exit(&spa_namespace_lock);
 		fnvlist_free(config);
 		cmn_err(CE_NOTE, "Can not parse the config for pool '%s'",
-		    pname);
+		    name);
 		return (error);
 	}