qat: Fixed Coverity reported issue

This patch provides fixes for following Coverity issues:
CID 1504073
CID 1504075
CID 1504076
CID 1504077

Patch co-authored by: Krzysztof Zdziarski <krzysztofx.zdziarski@intel.com>
Patch co-authored by: Michal Gulbicki <michalx.gulbicki@intel.com>
Patch co-authored by: Julian Grajkowski <julianx.grajkowski@intel.com>
Patch co-authored by: Piotr Kasierski <piotrx.kasierski@intel.com>
Patch co-authored by: Lukasz Kolodzinski <lukaszx.kolodzinski@intel.com>
Patch co-authored by: Karol Grzadziel <karolx.grzadziel@intel.com>

Fixes: a977168c48d4 ("qat: Add Intel® 4xxx Series platform support")
Reviewed by: markj
Sponsored by: Intel Corporation
Differential Revision: https://reviews.freebsd.org/D38339