avfilter/vf_fieldorder: Remove always-true check

A filter's formats.query callback is only called after all
the inputs and outputs have already been created.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavfilter/vf_fieldorder.c

@@ -46,7 +46,6 @@ static int query_formats(AVFilterContext *ctx)
 
     /** accept any input pixel format that is not hardware accelerated, not
      *  a bitstream format, and does not have vertically sub-sampled chroma */
-    if (ctx->inputs[0]) {
         const AVPixFmtDescriptor *desc = NULL;
         formats = NULL;
         while ((desc = av_pix_fmt_desc_next(desc))) {
@@ -59,9 +58,6 @@ static int query_formats(AVFilterContext *ctx)
                 return ret;
         }
         return ff_set_common_formats(ctx, formats);
-    }
-
-    return 0;
 }
 
 static int config_input(AVFilterLink *inlink)