demux: asf: fix keyframe waiting after a seek (fix #6647)
demux: asf: fix keyframe waiting after a seek (fix #6647)

Having pts doesn't mean we have a valid index.
Also, waiting 50 frames, including all streams is pointless.
We expect at least a keyframe within 60 sec on seek track.
This wait is lowered to 5 sec of data if we estimate a low
bandwidth (that one might need a better hint)

vlc-mirror/vlc,krichter722/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,krichter722/vlc,vlc-mirror/vlc,krichter722/vlc,shyamalschandra/vlc,shyamalschandra/vlc,vlc-mirror/vlc,vlc-mirror/vlc,jomanmuk/vlc-2.2,krichter722/vlc,jomanmuk/vlc-2.2,shyamalschandra/vlc,jomanmuk/vlc-2.2,xkfz007/vlc,vlc-mirror/vlc,vlc-mirror/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,shyamalschandra/vlc,jomanmuk/vlc-2.2,krichter722/vlc,jomanmuk/vlc-2.2,xkfz007/vlc,vlc-mirror/vlc,krichter722/vlc,jomanmuk/vlc-2.2,xkfz007/vlc,shyamalschandra/vlc,xkfz007/vlc,krichter722/vlc,shyamalschandra/vlc