[SCSI] qla2xxx: Correct NPIV support for recent ISPs.

Firmware will export to software the maximum number of vports
supported for any given firmware version and ISP type.  Use this
information rather than the current hardcoding of limitations
within the driver.

Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>