libs: encoder: increase bitrate prop max value
libs: encoder: increase bitrate prop max value

There are many profile levels that can support
more than 102400 kbps.  Thus, increase the max
allowed bitrate property value from 102400 kbps
to 2048000 kbps (same as msdk encoder plugins).

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