common: Move old EEPROM functions into a new header

These functions do not use driver model but are still used. Move them to a
new eeprom.h header file.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/board/ti/am43xx/board.c b/board/ti/am43xx/board.c
index 9353830..d12f1eb 100644
--- a/board/ti/am43xx/board.c
+++ b/board/ti/am43xx/board.c
@@ -8,6 +8,7 @@
  */
 
 #include <common.h>
+#include <eeprom.h>
 #include <env.h>
 #include <i2c.h>
 #include <init.h>