ALSA: memalloc: remove snd_dma_sg_ops declaration

snd_dma_sg_ops has been removed since
commit 2c95b92e ("ALSA: memalloc: Unify x86 SG-buffer handling
(take#3)"), so remove it.
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Link: https://lore.kernel.org/r/20220909035443.1065737-3-cuigaosheng1@huawei.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/memalloc_local.h

@@ -13,8 +13,4 @@ struct snd_malloc_ops {
 	void (*sync)(struct snd_dma_buffer *dmab, enum snd_dma_sync_mode mode);
 };
 
-#ifdef CONFIG_SND_DMA_SGBUF
-extern const struct snd_malloc_ops snd_dma_sg_ops;
-#endif
-
 #endif /* __MEMALLOC_LOCAL_H */