scsi: qedf: Wait for stag work during unload

If stag work is already scheduled and unload is called, it can lead to
issues as unload cleans up the work element. Wait for stag work to get
completed before cleanup during unload.

Signed-off-by: Saurav Kashyap <skashyap@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Link: https://lore.kernel.org/r/20240515091101.18754-3-skashyap@marvell.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>