cosmetics: Correct comments in decklink_dec

Signed-off-by: Timothy Gu <timothygu99@gmail.com>

libavdevice/decklink_dec.cpp

 /*
- * Blackmagic DeckLink output
+ * Blackmagic DeckLink input
  * Copyright (c) 2013-2014 Luca Barbato, Deti Fliegl
  *
  * This file is part of FFmpeg.
@@ -524,7 +524,7 @@ av_cold int ff_decklink_read_header(AVFormatContext *avctx)
 
     /* Get input device. */
     if (ctx->dl->QueryInterface(IID_IDeckLinkInput, (void **) &ctx->dli) != S_OK) {
-        av_log(avctx, AV_LOG_ERROR, "Could not open output device from '%s'\n",
+        av_log(avctx, AV_LOG_ERROR, "Could not open input device from '%s'\n",
                avctx->filename);
         ret = AVERROR(EIO);
         goto error;

libavdevice/decklink_dec.h

 /*
- * Blackmagic DeckLink output
+ * Blackmagic DeckLink input
  * Copyright (c) 2013-2014 Ramiro Polla
  *
  * This file is part of FFmpeg.

libavdevice/decklink_dec_c.c

 /*
- * Blackmagic DeckLink output
+ * Blackmagic DeckLink input
  * Copyright (c) 2014 Deti Fliegl
  *
  * This file is part of FFmpeg.