cosmetic: s/BOARD_LATE_INIT/CONFIG_BOARD_LATE_INIT

This renames BOARD_LATE_INIT to CONFIG_BOARD_LATE_INIT.
Along the way it removes some leftover

 #define BOARD_LATE_INIT		1

and adds some basic documentation for board specific
callbacks in README.

Signed-off-by: Helmut Raiger <helmut.raiger@hale.at>
Acked-by: Stefano Babic <sbabic@denx.de>
diff --git a/include/configs/VCMA9.h b/include/configs/VCMA9.h
index 183045b..8b8113d 100644
--- a/include/configs/VCMA9.h
+++ b/include/configs/VCMA9.h
@@ -76,7 +76,7 @@
 #define CONFIG_CMD_BSP
 #define CONFIG_CMD_NAND
 
-#define BOARD_LATE_INIT
+#define CONFIG_BOARD_LATE_INIT
 
 #define CONFIG_SYS_HUSH_PARSER
 #define CONFIG_SYS_PROMPT_HUSH_PS2 "> "