ALSA: pcmtest: Update comment about PCM copy ops

Just an update of a comment mentioning the old PCM callbacks to
correct to the new PCM copy ops.

Link: https://lore.kernel.org/r/20230815190136.8987-17-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/pcmtest.c

@@ -227,7 +227,7 @@ static void check_buf_block(struct pcmtst_buf_iter *v_iter, struct snd_pcm_runti
 
 /*
  * Fill buffer in the non-interleaved mode. The order of samples is C0, ..., C0, C1, ..., C1, C2...
- * The channel buffers lay in the DMA buffer continuously (see default copy_user and copy_kernel
+ * The channel buffers lay in the DMA buffer continuously (see default copy
  * handlers in the pcm_lib.c file).
  *
  * Here we increment the DMA buffer position every time we write a byte to any channel 'buffer'.