initcall: Drop use of header files

This file should not include header files. They have already been included
by the time initcall.h is included. Also, document how to enable debugging
in this file.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/initcall.h

@@ -8,12 +8,11 @@
 
 typedef int (*init_fnc_t)(void);
 
-#include <common.h>
-#include <initcall.h>
-#include <efi.h>
-
-DECLARE_GLOBAL_DATA_PTR;
-
+/*
+ * To enable debugging. add #define DEBUG at the top of the including file.
+ *
+ * To find a symbol, use grep on u-boot.map
+ */
 static inline int initcall_run_list(const init_fnc_t init_sequence[])
 {
 	const init_fnc_t *init_fnc_ptr;