common: board_r: drop initr_addr_map wrapper

Add a return value to init_addr_map and use it directly in the
post-relocation init sequence, rather than using a wrapper stub.

Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>