DSDT.asl should not report the AMD SB600/SB700 RTC as Intel PIIX4

DSDT.asl should not report the AMD SB600/SB700 RTC as Intel PIIX4
compatible. The extended cmos is accessed differently for AMD
and Intel RTCs. Not sure what if any OS cares about this distinction,
but non-Intel compatible seems like a safer way to report the AMD RTC.
Tested with Win7 on Mahogany_fam10 and kino-780am2-fam10.

Signed-off-by: Scott Duplichan <scott@notabs.org>
Acked-by: Marc Jones <marcj303@gmail.com>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@6046 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1