To enable this, alternative, configuration the U-Boot board configuration
file for lwmon5 includes the definitions of alternative addresses for header
(CONFIG_ALT_LH_ADDR) and buffer (CONFIG_ALT_LB_ADDR).
The Linux shall be configured with the CONFIG_ALT_LB_LOCATION option set,
and has the BOARD_ALT_LH_ADDR and BOARD_ALT_LB_ADDR constants defined in the
lwmon5 board-specific header (arch/ppc/platforms/4xx/lwmon5.h).
Signed-off-by: Yuri Tikhonov <yur@emcraft.com>