ALSA: memalloc: Fix a typo in snd_dma_buffer_sync() description

It caused a warning for kernel-doc build.

Fixes: a25684a9 ("ALSA: memalloc: Support for non-contiguous page allocation")
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20211019165402.4fa82c38@canb.auug.org.au
Link: https://lore.kernel.org/r/20211019060536.26089-2-tiwai@suse.deSigned-off-by: NTakashi Iwai <tiwai@suse.de>

sound/core/memalloc.c

@@ -196,7 +196,7 @@ EXPORT_SYMBOL(snd_dma_buffer_mmap);
 /**
  * snd_dma_buffer_sync - sync DMA buffer between CPU and device
  * @dmab: buffer allocation information
- * @mod: sync mode
+ * @mode: sync mode
  */
 void snd_dma_buffer_sync(struct snd_dma_buffer *dmab,
 			 enum snd_dma_sync_mode mode)