scsi: sd: Fix interpretation of VPD B9h length

Fixing the interpretation of the length of the B9h VPD page (Concurrent
Positioning Ranges). Adding 4 is necessary as the first 4 bytes of the page
is the header with page number and length information.  Adding 3 was likely
a misinterpretation of the SBC-5 specification which sets all offsets
starting at zero.

This fixes the error in dmesg:

[ 9.014456] sd 1:0:0:0: [sda] Invalid Concurrent Positioning Ranges VPD page

Link: https://lore.kernel.org/r/20220602225113.10218-4-tyler.erickson@seagate.com


Fixes: e815d365 ("scsi: sd: add concurrent positioning ranges support")
Cc: stable@vger.kernel.org
Tested-by: Michael English <michael.english@seagate.com>
Reviewed-by: Muhammad Ahmad <muhammad.ahmad@seagate.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Tyler Erickson <tyler.erickson@seagate.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>