StorageManager: fix android.process.media process stop while plug a discontinuous partitioned SD Card

While get volume state, throw an IllegalArgumentException, catch
this exception in StorageManager and return null to MtpService to
avoid process stoping.

Change-Id: I7d32e3007296eca5903e6753f6a3395be4bf48c9
Author: Gang Li <gang.g.li@intel.com>
Signed-off-by: Gang Li <gang.g.li@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: 47459