a52 plugin Unknown field card error

[GitHub issues - edited <github@xxxxxxxxxxxxxxxx>]

alsa-project/alsa-lib issue #405 was edited from DocMAX:

```
pcm.a52 {
  @args [CARD]
  @args.CARD {
    type string
  }
  type rate
  slave {
    pcm {
      type a52
      bitrate 448
      channels 6
      card $CARD
    }
    rate 48000
  }
}

a52:CARD=Adapter
    USB SPDIF Adapter
    Plugin to convert multichannel stream to A52 (AC3) bitstream

[root@desktop ~]# speaker-test -c6 -Da52

speaker-test 1.2.12

Playback device is a52
Stream parameters are 48000Hz, S16_LE, 6 channels
Using 16 octaves of pink noise
ALSA lib pcm_rate.c:1701:(_snd_pcm_rate_open) Unknown field card
Playback open error: -22,Invalid argument
```
how to fix this error?
running arch linux all updated

Issue URL     : https://github.com/alsa-project/alsa-lib/issues/405
Repository URL: https://github.com/alsa-project/alsa-lib