The following patch adds an explicit no list of arches who do not want
to have the "Enhanced Real Time Clock Support" RTC driver asked.  This
adds PPC32 (who for a long time had their own 'generic' RTC driver, and
then have adopted the genrtc driver) and PARISC (who have always used
the genrtc driver).  Per request of Peter Chubb, IA64 is on this list as
well.

The problem is that on some archs there is no hope of this driver
working, and having it compiled into the kernel can cause many different
problems.  On the other hand, there are some arches for whom that driver
does work, on some platforms.  So having an explicit yes list would
result in some rather ugly statements.