scsi: zfcp: Make the type for accessing request hashtable buckets size_t

scsi: zfcp: Make the type for accessing request hashtable buckets size_t

The appropriate type for array indices is 'size_t' and the current
implementation in 'zfcp_reqlist.h' mixes 'int' and 'unsigned int' in
different places to access the hashtable buckets of our internal request
hash table.

To prevent any confusion, change all places to 'size_t'.

Link: https://lore.kernel.org/r/64afe93f6263c6b07815937826cd7d5fc4f1a674.1677000450.git.bblock@linux.ibm.com
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>