scsi: target: iblock: Fix type of logs_per_phys

scsi: target: iblock: Fix type of logs_per_phys

According to ilog2() it expects 32/64 bit unsigned value.

"  147  * ilog2 - log base 2 of 32-bit or a 64-bit unsigned value"

Replace type of logs_per_phys from int to unsigned int.

Link: https://lore.kernel.org/r/20210228055645.22253-4-chaitanya.kulkarni@wdc.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>