ARM: introduce arch_early_init_r()

Introduce arch_early_init_r() function, which can be useful for doing
early initialization after relocation has happened.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/arch/arm/lib/board.c b/arch/arm/lib/board.c
index 024646c..f21591d 100644
--- a/arch/arm/lib/board.c
+++ b/arch/arm/lib/board.c
@@ -500,6 +500,10 @@
 	malloc_start = dest_addr - TOTAL_MALLOC_LEN;
 	mem_malloc_init (malloc_start, TOTAL_MALLOC_LEN);
 
+#ifdef CONFIG_ARCH_EARLY_INIT_R
+	arch_early_init_r();
+#endif
+
 #if !defined(CONFIG_SYS_NO_FLASH)
 	puts("Flash: ");