scsi: qla2xxx: Refactor asynchronous command initialization

Move common open-coded asynchronous command initializing code such as
setting up the timer and the done callback into one function. This is a
preparation step and allows us later on to change the low level error flow
handling at a central place.

Link: https://lore.kernel.org/r/20220110050218.3958-2-njavali@marvell.com
Cc: stable@vger.kernel.org
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Saurav Kashyap <skashyap@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>