From: Martin Schwidefsky <schwidefsky@de.ibm.com>

dasd driver fixes:
 - Remove additional dasd attributes for a ccw-device if the discipline
   (=driver) gets unloaded.
 - Fix race of dasd_generic_offline against dasd_open.
 - Remove irq_exit calls from diag interrupt handler. The irq_enter/
   irq_exit is done in the external interrupt handler.