Memory.java: disable remove unmount/mount button until unmount/mount is done

Disable unmount/mount button since the end user will click them again before
the setting is updated. So disable them until setting updated the status

Change-Id: I8bc6a06a76bd4636e4c65a334ee00503118d5bbf
Author: Chuanxiao Dong <chuanxiao.dong@intel.com>
Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Signed-off-by: Shuo Gao <shuo.gao@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 47861