Change "offet" into "offset" in a variable name.

Link: https://lore.kernel.org/r/20200518211712.11395-2-bvanassche@acm.org
Cc: Nilesh Javali <njavali@marvell.com>
Cc: Quinn Tran <qutran@marvell.com>
Cc: Martin Wilck <mwilck@suse.com>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Arun Easi <aeasi@marvell.com>
Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>