staging: unisys: visorbus: visorbus_main.c: Fix return values for checks in visorbus_register_visor_driver.

The error return values for the drv->probe, drv->remove, drv->pause
and drv->resume checks should be -EINVAL instead of -ENODEV.

Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sameer Wadgaonkar <sameer.wadgaonkar@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <timothy.sell@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/visorbus/visorbus_main.c

@@ -969,16 +969,16 @@ int visorbus_register_visor_driver(struct visor_driver *drv)
 		return -ENODEV;
 
 	if (!drv->probe)
-		return -ENODEV;
+		return -EINVAL;
 
 	if (!drv->remove)
-		return -ENODEV;
+		return -EINVAL;
 
 	if (!drv->pause)
-		return -ENODEV;
+		return -EINVAL;
 
 	if (!drv->resume)
-		return -ENODEV;
+		return -EINVAL;
 
 	drv->driver.name = drv->name;
 	drv->driver.bus = &visorbus_type;