ARM: mmp: fix potential NULL dereference

Fix the wrong logic: we should use || instead of &&

Cc: Leo Yan <leoy@marvell.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Yuanhan Liu <yliu.null@gmail.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>