scsi: csiostor: Fix wrong return value in csio_hw_prep_fw()

scsi: csiostor: Fix wrong return value in csio_hw_prep_fw()

BugLink: https://bugs.launchpad.net/bugs/1902115
[ Upstream commit 44f4daf8678ae5f08c93bbe70792f90cd88e4649 ]

On an error exit path, a negative error code should be returned instead of
a positive return value.

Link: https://lore.kernel.org/r/20200802111531.5065-1-tianjia.zhang@linux.alibaba.com
Fixes: f40e74ffa3de ("csiostor:firmware upgrade fix")
Cc: Praveen Madhavan <praveenm@chelsio.com>
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Ian May <ian.may@canonical.com>