x11grab: AVFormatParameters are always passed from av_open_input_stream(),

there is no need to check for it.

Originally committed as revision 22651 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavdevice/x11grab.c

@@ -110,7 +110,7 @@ x11grab_read_header(AVFormatContext *s1, AVFormatParameters *ap)
         return AVERROR(EIO);
     }
 
-    if (!ap || ap->width <= 0 || ap->height <= 0 || ap->time_base.den <= 0) {
+    if (ap->width <= 0 || ap->height <= 0 || ap->time_base.den <= 0) {
         av_log(s1, AV_LOG_ERROR, "AVParameters don't have video size and/or rate. Use -s and -r.\n");
         return AVERROR(EIO);
     }