common: Drop init.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/x86_64/cpu.c b/arch/x86/cpu/x86_64/cpu.c
index 4b64339..1b4d397 100644
--- a/arch/x86/cpu/x86_64/cpu.c
+++ b/arch/x86/cpu/x86_64/cpu.c
@@ -7,6 +7,7 @@
 #include <common.h>
 #include <cpu_func.h>
 #include <debug_uart.h>
+#include <init.h>
 
 /*
  * Global declaration of gd.