Staging: sxg: Add checksum control option through ethtool interface

* This patch adds support for controling checksum feature using the ethtool
  interface.

Signed-off-by: LinSysSoft Sahara Team <saharaproj@linsyssoft.com>
Signed-off-by: Mithlesh Thukral <mithlesh@linsyssoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>