dmaengine: virt-dma: move function declarations

We get 2 warnings when building kernel with W=1:
drivers/dma/virt-dma.c:22:14: warning: no previous prototype for 'vchan_tx_submit' [-Wmissing-prototypes]
drivers/dma/virt-dma.c:52:5: warning: no previous prototype for 'vchan_tx_desc_free' [-Wmissing-prototypes]

In fact, these two functions are incorrectly declared in a function.

So this patch moves function declarations out of this function.
Signed-off-by: NBaoyou Xie <baoyou.xie@linaro.org>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>

drivers/dma/virt-dma.h

@@ -45,6 +45,8 @@ static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
 struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
+extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
+extern int vchan_tx_desc_free(struct dma_async_tx_descriptor *);
 
 /**
  * vchan_tx_prep - prepare a descriptor
@@ -55,8 +57,6 @@ struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
 static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
 	struct virt_dma_desc *vd, unsigned long tx_flags)
 {
-	extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
-	extern int vchan_tx_desc_free(struct dma_async_tx_descriptor *);
 	unsigned long flags;
 
 	dma_async_tx_descriptor_init(&vd->tx, &vc->chan);