[SCSI] qla2xxx: Convert vport_sem to a mutex

The semaphore vport_sem is used as a mutex.  Convert it to the
mutex API.

Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>