Add a GTOD clocksource driver based on the Geode SCx200's Hi-Res Timer.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>