Fix the I/O hang that arises because of the MSIx vector not having a mapped
online CPU upon receiving completion.

SCSI cmds take the blk_mq route, which is setup during init. Reserved cmds
fetch the vector_no from mq_map after init is complete. Before init, they
have to use 0 - as per the norm.
Reviewed-by: Gilbert Wu <gilbert.wu@microchip.com>
Signed-off-by: Sagar Biradar <Sagar.Biradar@microchip.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20230519230834.27436-1-sagar.biradar@microchip.comSigned-off-by: Martin K. Petersen <martin.petersen@oracle.com>