vold2: Fix issue with destroying / unmounting asec

Signed-off-by: San Mehat <san@google.com>
diff --git a/Devmapper.cpp b/Devmapper.cpp
index 74ed4fb..9dd8ef3 100644
--- a/Devmapper.cpp
+++ b/Devmapper.cpp
@@ -190,7 +190,9 @@
     ioctlInit(io, 4096, name, 0);
 
     if (ioctl(fd, DM_DEV_REMOVE, io)) {
-        LOGE("Error destroying device mapping (%s)", strerror(errno));
+        if (errno != ENXIO) {
+            LOGE("Error destroying device mapping (%s)", strerror(errno));
+        }
         free(buffer);
         close(fd);
         return -1;