[SCSI] ibmvfc: Fix log level filtering

The ibmvfc log level filtering logic was reversed. The log_level scsi
host parameter should result in more verbose logs when log_level is
larger, not smaller.

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