Intel ethernet adapter: Update MAINTAINERS

Another team member unfortunately left: update MAINTAINERS.

Condense the 3 lists down to a single list for all our drivers.

Point to our new sourceforge index page which is slightly
better navigateable than the sf.net project page.

Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>