ACPICA: Add a check for a null node during namespace walk.

Mostly for consistency. ACPICA BZ 1042.

Actually, currently no one is experiencing problem without this check
as the obj_handle is guaranteed to be valid.

References: https://bugs.acpica.org/show_bug.cgi?id=1042
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/nsdump.c

@@ -715,6 +715,13 @@ acpi_ns_dump_one_object_path(acpi_handle obj_handle,
 	}
 
 	node = acpi_ns_validate_handle(obj_handle);
+	if (!node) {
+
+		/* Ignore bad node during namespace walk */
+
+		return (AE_OK);
+	}
+
 	pathname = acpi_ns_get_external_pathname(node);
 
 	path_indent = 1;