MIPS: sni: Remove the read_persistent_clock()

The dummy read_persistent_clock() uses a timespec, which is not year
2038 safe on 32bit systems. Thus remove this obsolete interface.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/19114/Signed-off-by: James Hogan <jhogan@kernel.org>

arch/mips/sni/time.c

@@ -171,9 +171,3 @@ void __init plat_time_init(void)
 	}
 	setup_pit_timer();
 }
-
-void read_persistent_clock(struct timespec *ts)
-{
-	ts->tv_sec = -1;
-	ts->tv_nsec = 0;
-}