staging: comedi: ni_mio_common: remove devpriv macro

The ni_mio_common.c file is #include'd by the ni_atmio, ni_mio_cs,
and ni_pcimio drivers. Those drivers all have a devpriv macro of
this type:

This macro relies on a local variable having a specific name.
Remove its use in all the files by replacing it with a local
variable.

Some of the functions in ni_mio_common.c don't always use the
devpriv variable due to differences in how the low-level i/o
is handled by the driver. Tag the variable in those functions
with __maybe_unused to avoid compile warnings.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_atmio.c

@@ -284,8 +284,6 @@ struct ni_private {
 
 };
 
-#define devpriv ((struct ni_private *)dev->private)
-
 /* How we access registers */
 
 #define ni_writel(a, b)		(outl((a), (b)+dev->iobase))
@@ -303,6 +301,7 @@ struct ni_private {
 
 static void ni_atmio_win_out(struct comedi_device *dev, uint16_t data, int addr)
 {
+	struct ni_private *devpriv = dev->private;
 	unsigned long flags;
 
 	spin_lock_irqsave(&devpriv->window_lock, flags);
@@ -317,6 +316,7 @@ static void ni_atmio_win_out(struct comedi_device *dev, uint16_t data, int addr)
 
 static uint16_t ni_atmio_win_in(struct comedi_device *dev, int addr)
 {
+	struct ni_private *devpriv = dev->private;
 	unsigned long flags;
 	uint16_t ret;
 
@@ -406,16 +406,17 @@ static int ni_getboardtype(struct comedi_device *dev)
 static int ni_atmio_attach(struct comedi_device *dev,
 			   struct comedi_devconfig *it)
 {
+	struct ni_private *devpriv;
 	struct pnp_dev *isapnp_dev;
 	int ret;
 	unsigned long iobase;
 	int board;
 	unsigned int irq;
 
-	/* allocate private area */
 	ret = ni_alloc_private(dev);
-	if (ret < 0)
+	if (ret)
 		return ret;
+	devpriv = dev->private;
 
 	devpriv->stc_writew = &ni_atmio_win_out;
 	devpriv->stc_readw = &ni_atmio_win_in;
@@ -499,6 +500,8 @@ static int ni_atmio_attach(struct comedi_device *dev,
 
 static void ni_atmio_detach(struct comedi_device *dev)
 {
+	struct ni_private *devpriv = dev->private;
+
 	mio_common_detach(dev);
 	if (dev->iobase)
 		release_region(dev->iobase, NI_SIZE);