vxge: enable rxhash

Enable RSS hashing and add ability to pass up the adapter calculated rx
hash up the network stack (if feature is available).  Add the ability to
enable/disable feature via ethtool, which requires that the adapter is
not running at the time.  Other miscellaneous cleanups and fixes
required to get RSS working.

Signed-off-by: Jon Mason <jon.mason@exar.com>
Signed-off-by: Ram Vepa <ram.vepa@exar.com>
Signed-off-by: David S. Miller <davem@davemloft.net>