fftools/cmdutils: Don't access AV(In|Out)putformat.get_device_list

It is not part of the public API.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

fftools/cmdutils.c

@@ -2230,14 +2230,8 @@ static int print_device_sources(const AVInputFormat *fmt, AVDictionary *opts)
         return AVERROR(EINVAL);
 
     printf("Auto-detected sources for %s:\n", fmt->name);
-    if (!fmt->get_device_list) {
-        ret = AVERROR(ENOSYS);
-        printf("Cannot list sources. Not implemented.\n");
-        goto fail;
-    }
-
     if ((ret = avdevice_list_input_sources(fmt, NULL, opts, &device_list)) < 0) {
-        printf("Cannot list sources.\n");
+        printf("Cannot list sources: %s\n", av_err2str(ret));
         goto fail;
     }
 
@@ -2260,14 +2254,8 @@ static int print_device_sinks(const AVOutputFormat *fmt, AVDictionary *opts)
         return AVERROR(EINVAL);
 
     printf("Auto-detected sinks for %s:\n", fmt->name);
-    if (!fmt->get_device_list) {
-        ret = AVERROR(ENOSYS);
-        printf("Cannot list sinks. Not implemented.\n");
-        goto fail;
-    }
-
     if ((ret = avdevice_list_output_sinks(fmt, NULL, opts, &device_list)) < 0) {
-        printf("Cannot list sinks.\n");
+        printf("Cannot list sinks: %s\n", av_err2str(ret));
         goto fail;
     }