sparc32: use RTC subsystem

Use rtc subsystem for sparc32 architecture.
Actually, only one driver is needed: m48t59
as it supports the most common clocks on sparc32
machines: m48t08 and m48t02.

[ Add proper RTC layer calls to set_rtc_mmss() -DaveM ]

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>