Replace one more occurrence of -1 with PIX_FMT_NONE.

Fixes icc warning #188: enumerated type mixed with another type 


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@13136 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/dnxhdenc.c

@@ -845,6 +845,6 @@ AVCodec dnxhd_encoder = {
     dnxhd_encode_init,
     dnxhd_encode_picture,
     dnxhd_encode_end,
-    .pix_fmts = (enum PixelFormat[]){PIX_FMT_YUV422P, -1},
+    .pix_fmts = (enum PixelFormat[]){PIX_FMT_YUV422P, PIX_FMT_NONE},
     .long_name = "VC3/DNxHD",
 };