Fix failure erasing SD in Factory reset

Initialize mIsDecrypted to prevent from formatting SD failure

Change-Id: I30851e6b01b0999bf0b8c1e4b8e3f3a976a41ad1
Signed-off-by: Cylen Yao <cylen.yao@mediatek.com>
(cherry picked from commit 5dbcbd03149af50db42dadeebf565333ce399182)

DirectVolume.cpp

@@ -79,6 +79,7 @@ DirectVolume::DirectVolume(VolumeManager *vm, const fstab_rec* rec, int flags) :
     mDiskMajor = -1;
     mDiskMinor = -1;
     mDiskNumParts = 0;
+    mIsDecrypted = 0;
 
     if (strcmp(rec->mount_point, "auto") != 0) {
         ALOGE("Vold managed volumes must have auto mount point; ignoring %s",