asus_acpi: fix a memory leak in asus_hotk_get_info()

In the case of no match ( hotk->model == END_MODEL ), model sholud be
kfreed before return AE_OK.

This patch includes below fixes:

1. adds a missing kfree(model) before return AE_OK.

2. asus_hotk_get_info should return int, thus return 0 instead of AE_OK.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: Corentin Chary <corentincj@iksaif.net>
Cc: Karol Kozimor <sziwan@users.sourceforge.net>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Garrett <mjg@redhat.com>