acer-wmi: fix memory leaks in WMID_set_capabilities and get_wmid_devices

When acpi_evaluate_object() is passed ACPI_ALLOCATE_BUFFER, the caller
must kfree the returned buffer if AE_OK is returned.

The callers of wmi_query_block() pass ACPI_ALLOCATE_BUFFER, and thus must
check its return value before accessing or kfree() on the buffer.

This patch adds a missing kfree(out.pointer) before exit
WMID_set_capabilities() and get_wmid_devices().

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Carlos Corbacho <carlos@strangeworlds.co.uk>
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Garrett <mjg@redhat.com>