staging: kpc2000: added a helper to get struct kp2000_device from struct device.

The attribute call-backs all use the same formula to get the pcard from
dev:

  struct pci_dev *pdev = to_pci_dev(dev);
  struct kp2000_device *pcard;

  if (!pdev)
    return -ENXIO;
  pcard = pci_get_drvdata(pdev);
  if (!pcard)
    return -ENXIO;

Added a function to reduce the duplicated code.
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/kpc2000/kpc2000/core.c

@@ -29,15 +29,21 @@
  * SysFS Attributes
  ******************************************************/
 
-static ssize_t show_attr(struct device *dev, struct device_attribute *attr,
-			 char *buf)
+static struct kp2000_device *get_pcard(struct device *dev)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
-	struct kp2000_device *pcard;
 
 	if (!pdev)
-		return -ENXIO;
-	pcard = pci_get_drvdata(pdev);
+		return NULL;
+
+	return pci_get_drvdata(pdev);
+}
+
+static ssize_t show_attr(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct kp2000_device *pcard = get_pcard(dev);
+
 	if (!pcard)
 		return -ENXIO;
 
@@ -72,14 +78,9 @@ static ssize_t show_attr(struct device *dev, struct device_attribute *attr,
 static ssize_t show_cpld_config_reg(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
-	struct pci_dev *pdev = to_pci_dev(dev);
-	struct kp2000_device *pcard;
+	struct kp2000_device *pcard = get_pcard(dev);
 	u64 val;
 
-	if (!pdev)
-		return -ENXIO;
-
-	pcard = pci_get_drvdata(pdev);
 	if (!pcard)
 		return -ENXIO;
 
@@ -91,14 +92,10 @@ static ssize_t cpld_reconfigure(struct device *dev,
 				struct device_attribute *attr,
 				const char *buf, size_t count)
 {
-	struct pci_dev *pdev = to_pci_dev(dev);
+	struct kp2000_device *pcard = get_pcard(dev);
 	long wr_val;
-	struct kp2000_device *pcard;
 	int rv;
 
-	if (!pdev)
-		return -ENXIO;
-	pcard = pci_get_drvdata(pdev);
 	if (!pcard)
 		return -ENXIO;