lavfi/kerndeint: use av_pix_fmt_desc_get instead of directly accessing the table

Fixes FATE in MSVC DLL builds.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/vf_kerndeint.c

@@ -96,7 +96,7 @@ static int query_formats(AVFilterContext *ctx)
 static int config_props(AVFilterLink *inlink)
 {
     KerndeintContext *kerndeint = inlink->dst->priv;
-    const AVPixFmtDescriptor *desc = &av_pix_fmt_descriptors[inlink->format];
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
     int ret;
 
     kerndeint->vsub = desc->log2_chroma_h;