powerpc, 8xx: fix missing function declarations.

Add missing .h and add missing declarations in .h
Declare local functions as static.  Make interrupt_init_cpu function
signatures consistent with how decrementer_count is declared.

Based on warnings reported by 'make C=2'

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[trini: drop cpu_init_f as 8xx/83xx are different from the rest, rework
interrupt_init_cpu/decrementer_count]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/powerpc/cpu/mpc8xx/traps.c b/arch/powerpc/cpu/mpc8xx/traps.c
index ebf4e41..23646ad 100644
--- a/arch/powerpc/cpu/mpc8xx/traps.c
+++ b/arch/powerpc/cpu/mpc8xx/traps.c
@@ -52,7 +52,7 @@
 	printf("\n");
 }
 
-void show_regs(struct pt_regs *regs)
+static void show_regs(struct pt_regs *regs)
 {
 	int i;