cros_ec: Remove unused cros_ec_board_init() function

Now that driver model handles cros_ec init, we can drop this special code.

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

include/cros_ec.h

@@ -362,13 +362,6 @@ int cros_ec_set_ldo(struct cros_ec_dev *dev, uint8_t index, uint8_t state);
  */
 int cros_ec_get_ldo(struct cros_ec_dev *dev, uint8_t index, uint8_t *state);
 
-/**
- * Initialize the Chrome OS EC at board initialization time.
- *
- * @return 0 if ok, -ve on error
- */
-int cros_ec_board_init(void);
-
 /**
  * Get access to the error reported when cros_ec_board_init() was called
  *