vxge: always enable hardware time stamp

Hardware time stamp calculation can only be enabled by the privileged
function. Enable it always by default and simply use the ethtool
interface to set a flag to indicate whether or not the respective
function driver should indicate the timestamp along with the received
packet.

Also, make certain fields in vxge_hw_device_config bit-fields to reduce
the size of the struct.

Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: David S. Miller <davem@davemloft.net>