Staging: sxg: New SXG_SGL design and MAC Header changes

* This patch introduces the new SXG_SGL design.
	* Related changes to sxg_scatter_gather structure.
	* Introduced PSXG_X64_SGL changes which are x64 friendly
* Setting the MAC HEADER pointer properly in skb before giving to higher
  layers.

Signed-off-by: Michael Miles <mmiles@alacritech.com>
Signed-off-by: LinSysSoft Sahara Team <saharaproj@linsyssoft.com>
Signed-off-by: Christopher Harrer <charrer@alacritech.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>