QSVDeintContext and VPPContext have the same base context, and all
features in deinterlace_qsv are implemented in vpp_qsv filter,  so
deinterlace_qsv can be taken as a special case of vpp_qsv filter, and we
may use VPPContext with a different option array, preinit callback and
support pixel formats to implement deinterlace_qsv, then remove
QSVDeintContext.
Signed-off-by: Haihao Xiang <haihao.xiang@intel.com>