gvt-fixes-2018-01-08

- clear shadow entry for post-sync (Zhi)
- fix stack out-of-bound warning in cmd parser (Changbin)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180108061130.ucwtumhpbfbu4psu@zhen-hp.sh.intel.com