ACPI / TPM: fix memory leak when walking ACPI namespace

commit df45c712d1f4ef37714245fb75de726f4ca2bf8d upstream.

In function ppi_callback(), memory allocated by acpi_get_name() will get
leaked when current device isn't the desired TPM device, so fix the
memory leak.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>