As per the top level U-Boot README "Board Initialisation Flow"
section, board_init_f() should return without calling board_init_r()
directly. Clearing BSS and calling board_init_r() will be done in
crt0_64.S.
Signed-off-by: Gong Qianyu <Qianyu.Gong@nxp.com> Reviewed-by: York Sun <york.sun@nxp.com>