Blackfin arch: add const to some function prototype and struct dma_channel

Signed-off-by: Michael McTernan <mmcternan@airvana.com>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

arch/blackfin/include/asm/dma.h

@@ -135,7 +135,7 @@ typedef irqreturn_t(*dma_interrupt_t) (int irq, void *dev_id);
 
 struct dma_channel {
 	struct mutex dmalock;
-	char *device_id;
+	const char *device_id;
 	enum dma_chan_status chan_status;
 	struct dma_register *regs;
 	struct dmasg *sg;		/* large mode descriptor */
@@ -191,7 +191,7 @@ void free_dma(unsigned int channel);
 int dma_channel_active(unsigned int channel); /* check if a channel is in use */
 void disable_dma(unsigned int channel);
 void enable_dma(unsigned int channel);
-int request_dma(unsigned int channel, char *device_id);
+int request_dma(unsigned int channel, const char *device_id);
 int set_dma_callback(unsigned int channel, dma_interrupt_t callback,
 		     void *data);
 void dma_disable_irq(unsigned int channel);

arch/blackfin/kernel/bfin_dma_5xx.c

@@ -116,7 +116,7 @@ late_initcall(proc_dma_init);
 /*------------------------------------------------------------------------------
  *	Request the specific DMA channel from the system.
  *-----------------------------------------------------------------------------*/
-int request_dma(unsigned int channel, char *device_id)
+int request_dma(unsigned int channel, const char *device_id)
 {
 	pr_debug("request_dma() : BEGIN \n");