scsi: qla2xxx: Fix the code that reads from mailbox registers

Make the MMIO accessors strongly typed such that the compiler checks
whether the accessor function is used that matches the register width. Fix
those MMIO accesses where another number of bits was read or written than
the size of the register.

Link: https://lore.kernel.org/r/20200518211712.11395-11-bvanassche@acm.org


Cc: Nilesh Javali <njavali@marvell.com>
Cc: Quinn Tran <qutran@marvell.com>
Cc: Martin Wilck <mwilck@suse.com>
Cc: Roman Bolshakov <r.bolshakov@yadro.com>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>