board/apollon/sys_info.c: Fix GCC 4.6 build warning

Fix:
sys_info.c: In function 'display_board_info':
sys_info.c:260:16: warning: variable 'db_s' set but not used
[-Wunused-but-set-variable]

Also fix resulting warnings:
sys_info.c:251:7: warning: unused variable 'db_ip' [-Wunused-variable]
sys_info.c:250:7: warning: unused variable 'db_men' [-Wunused-variable]

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Kyungmin Park <kyungmin.park@samsung.com>