Staging: sxg: Fix the module in Kconfig file for Sahara SXG driver

* Update the module name in Kconfig help section.
  This is a classic case of documentation keeping out of pace with
  development
  And this was overlooked by me ages ago when we had fixed the Makefile for
  sxg_ethtool to compile.

Signed-off-by: Mithlesh Thukral <mithlesh@linsyssoft.com>
Cc: Christopher Harrer <charrer@alacritech.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>