staging: comedi: comedi_fc: cfc_write_array_to_buffer() data is const

The `data` pointer of `cfc_write_array_to_buffer()` ought to point to
`const` data.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/comedi_fc.c

@@ -24,7 +24,7 @@
 
 /* Writes an array of data points to comedi's buffer */
 unsigned int cfc_write_array_to_buffer(struct comedi_subdevice *s,
-				       void *data, unsigned int num_bytes)
+				       const void *data, unsigned int num_bytes)
 {
 	struct comedi_async *async = s->async;
 	unsigned int retval;

drivers/staging/comedi/drivers/comedi_fc.h

@@ -35,8 +35,9 @@ static inline void cfc_inc_scan_progress(struct comedi_subdevice *s,
 }
 
 /* Writes an array of data points to comedi's buffer */
-unsigned int cfc_write_array_to_buffer(struct comedi_subdevice *,
-				       void *data, unsigned int num_bytes);
+unsigned int cfc_write_array_to_buffer(struct comedi_subdevice *s,
+				       const void *data,
+				       unsigned int num_bytes);
 
 static inline unsigned int cfc_write_to_buffer(struct comedi_subdevice *s,
 					       unsigned short data)