[SCSI] qla2xxx: Refactor qla data structures

Following changes have been made to the qla2xxx FC driver in
preparation for the multi- queue and future SR IOV hardware.

1. scsi_qla_host structure has been changed to contain scsi host
   specific data only.

2. A new structure, qla_hw_data is created to contain HBA specific
   hardware data.

3. Request and response IO specific data strucures are created.

4. The global list of fcports for the hba is not maintained anymore,
   instead a fcport list is construted on per scsi_qla_host.

Signed-of-by: Anirban Chakraborty <anirban.chakraborty@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>