ethtool: Support for configurable RSS hash key

This ethtool patch primarily copies the ioctl command data structures
from/to the User space and invokes the driver hook.

Signed-off-by: Venkat Duvvuru <VenkatKumar.Duvvuru@Emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>