lavc: use designated initialisers for all codecs.

It's more readable and less prone to breakage.
diff --git a/libavcodec/v210x.c b/libavcodec/v210x.c
index e3b1a3c..959dec5 100644
--- a/libavcodec/v210x.c
+++ b/libavcodec/v210x.c
@@ -133,14 +133,12 @@
 }
 
 AVCodec ff_v210x_decoder = {
-    "v210x",
-    AVMEDIA_TYPE_VIDEO,
-    CODEC_ID_V210X,
-    0,
-    decode_init,
-    NULL,
-    decode_close,
-    decode_frame,
-    CODEC_CAP_DR1,
+    .name           = "v210x",
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = CODEC_ID_V210X,
+    .init           = decode_init,
+    .close          = decode_close,
+    .decode         = decode_frame,
+    .capabilities   = CODEC_CAP_DR1,
     .long_name = NULL_IF_CONFIG_SMALL("Uncompressed 4:2:2 10-bit"),
 };