[MIPS] Alchemy: Convert from plat_timer_setup to plat_time_init.

The old plat_timer_setup hook is no longer getting called so the Alchemy
time initialization was getting skipped.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/au1000/common/time.c

@@ -228,7 +228,7 @@ unsigned long cal_r4koff(void)
 	return (cpu_speed / HZ);
 }
 
-void __init plat_timer_setup(struct irqaction *irq)
+void __init plat_time_init(void)
 {
 	unsigned int est_freq;