USB: make drivers/usb/input/wacom_sys.c:wacom_sys_irq() static

This patch makes the needlessly global wacom_sys_irq() static.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/input/wacom_sys.c b/drivers/usb/input/wacom_sys.c
index 3498b89..e7cc20a 100644
--- a/drivers/usb/input/wacom_sys.c
+++ b/drivers/usb/input/wacom_sys.c
@@ -42,7 +42,7 @@
 	return wcombo->wacom->dev;
 }
 
-void wacom_sys_irq(struct urb *urb)
+static void wacom_sys_irq(struct urb *urb)
 {
 	struct wacom *wacom = urb->context;
 	struct wacom_combo wcombo;