ahci: workarounds for mcp65

MCP65 ahci can do NCQ but doesn't set the CAP bit and rev A0 and A1
can't do MSI but have MSI capability.  Implement AHCI_HFLAG_YES_NCQ
and apply appropriate workarounds.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Peer Chen <pchen@nvidia.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>