[MIPS] Replace board_timer_setup function pointer by plat_timer_setup.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

---
diff --git a/arch/mips/dec/time.c b/arch/mips/dec/time.c
index 76e4d09..5729474 100644
--- a/arch/mips/dec/time.c
+++ b/arch/mips/dec/time.c
@@ -186,7 +186,7 @@
 
 EXPORT_SYMBOL(do_settimeofday);
 
-void __init dec_timer_setup(struct irqaction *irq)
+void __init plat_timer_setup(struct irqaction *irq)
 {
 	setup_irq(dec_interrupt[DEC_IRQ_RTC], irq);