libswscale/utils: Fix bayer to yuvj

Fixes: out of array access.

Earlier code assumes that a unscaled bayer to yuvj420 converter exists
but the later code then skips yuvj420

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit e9cc9e492f)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libswscale/utils.c

@@ -1730,7 +1730,8 @@ static av_cold int sws_init_single_context(SwsContext *c, SwsFilter *srcFilter,
     /* unscaled special cases */
     if (unscaled && !usesHFilter && !usesVFilter &&
         (c->srcRange == c->dstRange || isAnyRGB(dstFormat) ||
-         isFloat(srcFormat) || isFloat(dstFormat))){
+         isFloat(srcFormat) || isFloat(dstFormat) || isBayer(srcFormat))){
+
         ff_get_unscaled_swscale(c);
 
         if (c->convert_unscaled) {