Add defines to allow reading recovery mode (RCM) boot type from the boot
information table (BIT) written by the boot ROM (BR) to the IRAM.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>