[SCSI] 3w-9xxx: add MSI support and misc fixes

This patch for the 3w-9xxx scsi driver applies on top of the
BKL-pushdown changes in -git9.

This patch does the following:

- Increase max AENs drained to 256.
- Add MSI support and "use_msi" module parameter.
- Fix bug in twa_get_param() on 4GB+.
- Use pci_resource_len() for ioremap().

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>