[POWERPC] Revert "[POWERPC] Add powerpc get/set_rtc_time interface to new generic rtc class"

This reverts commit 7a69af63.

As advised by David Brownell:

http://marc.theaimsgroup.com/?l=linux-kernel&m=116387226902131&w=2



Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>