crypto: qat - remove incorrect __exit markup

PCI bus is hot-pluggable, and even if it wasn't one can still unbind the
device from driver via sysfs, so we should not make driver's remove
method as __exit.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>