[SCSI] qla2xxx: Remove mirrored field vp_idx from struct fc_port.

The field vp_idx in struct fc_port is a redundant/mirror copy of
the same field in struct scsi_qla_host;

struct fc_port has a pointer vha to scsi_qla_host which allows
the original copy of vp_idx to be readily accessed.

Signed-off-by: Joe Carnuccio <joe.carnuccio@qlogic.com>
Signed-off-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>