avcodec/v4l2_context: Use av_freep()

Reviewed-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Andriy Gelman <andriy.gelman@gmail.com>

libavcodec/v4l2_context.c

@@ -685,8 +685,7 @@ void ff_v4l2_context_release(V4L2Context* ctx)
     if (ret)
         av_log(logger(ctx), AV_LOG_WARNING, "V4L2 failed to unmap the %s buffers\n", ctx->name);
 
-    av_free(ctx->buffers);
-    ctx->buffers = NULL;
+    av_freep(&ctx->buffers);
 }
 
 int ff_v4l2_context_init(V4L2Context* ctx)
@@ -743,8 +742,7 @@ int ff_v4l2_context_init(V4L2Context* ctx)
 error:
     v4l2_release_buffers(ctx);
 
-    av_free(ctx->buffers);
-    ctx->buffers = NULL;
+    av_freep(&ctx->buffers);
 
     return ret;
 }