sky2: support for new Optima chipsets (EXPERIMENTAL)

This is a backport from the vendor driver of support for the newer Optima
(Prime and 2) chipsets. It also includes some setup changes for the
current Optima chip as well. The code and comments intentionally
mirror the vendor sk98lin driver to allow for easier maintenance.

Although this adds support for new chip id's, these chip id's are not
used by any of the current PCI device id's listed in the driver.
The patch is just to get initial infrastructure in place to handle them
when they come.

I don't have access to any of this hardware to actually test it yet.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>