sparc32: fix sparse warnings in time_32.c

Fix following warnings:
time_32.c:63:1: warning: symbol 'rtc_lock' was not declared. Should it be static?
time_32.c:357:13: warning: symbol 'time_init' was not declared. Should it be static?
time_32.c:148:16: warning: dereference of noderef expression

Add extern definition of rtc_lock in mc146818rtc.h.
time_init() is called from init/main.c - add prototype to kernel.h.
Use proper u32 __iomem * for master_l10_counter.
Fix all users.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>