ahci: clean up board IDs

ahci over time has grown a number of board IDs and it's a bit of mess
right now.  Clean it up such that,

* board_id_* now live in a separate enum board_ids and numbers are
  assigned automatically.

* Board IDs assigned to features are separated from the ones assigned
  to specific implementations and both are ordered alphabetically.

* For NV MCPs, define per-generation alias board_ids and assign
  matching aliases in the pci id table.  This makes mcp_linux, 67-73
  use board_ahci_mcp65 instead of board_ahci_yesncq.  Both are
  identical in content.

* Kill now unused board_ahci_nopmp and board_ahci_yesncq.

This patch doesn't cause any functional change but will make future
changes to board_ids and quirks much less painful.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Peer Chen <pchen@nvidia.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>