common: move init_helpers.h prototypes in init.h

Merge init_helpers.h in the new file init.h
with only prototypes for init_cache_f_r
used in common/board_f.c

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/include/init.h b/include/init.h
index d54d519..147ae6b 100644
--- a/include/init.h
+++ b/include/init.h
@@ -101,6 +101,13 @@
  */
 int arch_reserve_stacks(void);
 
+/**
+ * init_cache_f_r() - Turn on the cache in preparation for relocation
+ *
+ * @return 0 if OK, -ve on error
+ */
+int init_cache_f_r(void);
+
 int print_cpuinfo(void);
 int timer_init(void);
 int reserve_mmu(void);
diff --git a/include/init_helpers.h b/include/init_helpers.h
deleted file mode 100644
index 3efcfdd..0000000
--- a/include/init_helpers.h
+++ /dev/null
@@ -1,18 +0,0 @@
-/*
- * (C) Copyright 2011
- * Graeme Russ, <graeme.russ@gmail.com>
- *
- * SPDX-License-Identifier:	GPL-2.0+
- */
-
-#ifndef _INIT_HELPERS_H_
-#define _INIT_HELPERS_H_
-
-/**
- * init_cache_f_r() - Turn on the cache in preparation for relocation
- *
- * @return 0 if OK, -ve on error
- */
-int init_cache_f_r(void);
-
-#endif	/* _INIT_HELPERS_H_ */