[MIPS] Deforest the function pointer jungle in the time code.

Hard to follow who is pointing what to where and why so it's simply getting
in the way of the time code renovation.

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

arch/mips/bcm47xx/time.c

@@ -28,8 +28,7 @@
 #include <asm/time.h>
 #include <bcm47xx.h>
 
-void __init
-bcm47xx_time_init(void)
+void __init plat_time_init(void)
 {
 	unsigned long hz;