libs: encoder: h264fei: remove unnecessary check
libs: encoder: h264fei: remove unnecessary check

Issue detected by Coverity

There may be a null pointer dereference, or else the comparison
against null is unnecessary.

In gst_vaapi_encoder_h264_fei_encode: All paths that lead to this null
pointer comparison already dereference the pointer earlier

GStreamer/gstreamer-vaapi,ceyusa/gstreamer-vaapi,ceyusa/gstreamer-vaapi,GStreamer/gstreamer-vaapi