ACPICA: Namespace: Add acpi_ns_handle_to_name()

ACPICA commit f9fe27a68a90c9d32dd3156241a5e788fb6956ea

This patch adds acpi_ns_handle_to_name() so that in the acpi_get_name():
1. Logics can be made simpler,
2. Lock held for acpi_ns_handle_to_name() can also be applied to
   acpi_ns_handle_to_pathname().
The lock might be useless (see Link 1 below), but kept as acpi_get_name()
is an external API. Except the lock correction, this patch is a functional
no-op. BZ 1182, Lv Zheng.

Link: https://github.com/acpica/acpica/commit/f9fe27a6
Link: https://bugs.acpica.org/show_bug.cgi?id=1182

 [# 1]
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>