[SCSI] ibmvscsi: Make max_requests module parameter more accurate

In a previous patch to fix an issue with error recovery,
the behavior of the max_requests module paramater was also
changed. If, for some reason, max_requests is set to one by
the user, we will end up with a negative number for can_queue.
Fix this by making max_requests not include the two event structs
needed to do error recovery.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>