scsi: qla2xxx: Fix error return code in qla82xx_write_flash_dword()

Fix to return a negative error code from the error handling case instead of
0 as done elsewhere in this function.

Link: https://lore.kernel.org/r/20210514090952.6715-1-thunder.leizhen@huawei.com
Fixes: a9083016

 ("[SCSI] qla2xxx: Add ISP82XX support.")
Reported-by: Hulk Robot <hulkci@huawei.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>