dmaengine: idxd: make idxd_register/unregister_dma_channel() static

Since idxd_register/unregister_dma_channel() are only called locally, make
them static.

Reported-by: kernel test robot <[e-mail]>
Signed-off-by: Dave Jiang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/idxd/dma.c

···
 	dma_async_device_unregister(&idxd->idxd_dma->dma);
 }
 
-int idxd_register_dma_channel(struct idxd_wq *wq)
+static int idxd_register_dma_channel(struct idxd_wq *wq)
 {
 	struct idxd_device *idxd = wq->idxd;
 	struct dma_device *dma = &idxd->idxd_dma->dma;
···
 	return 0;
 }
 
-void idxd_unregister_dma_channel(struct idxd_wq *wq)
+static void idxd_unregister_dma_channel(struct idxd_wq *wq)
 {
 	struct idxd_dma_chan *idxd_chan = wq->idxd_chan;
 	struct dma_chan *chan = &idxd_chan->chan;

drivers/dma/idxd/idxd.h

···
 /* dmaengine */
 int idxd_register_dma_device(struct idxd_device *idxd);
 void idxd_unregister_dma_device(struct idxd_device *idxd);
-int idxd_register_dma_channel(struct idxd_wq *wq);
-void idxd_unregister_dma_channel(struct idxd_wq *wq);
 void idxd_parse_completion_status(u8 status, enum dmaengine_tx_result *res);
 void idxd_dma_complete_txd(struct idxd_desc *desc,
 			   enum idxd_complete_type comp_type, bool free_desc);