Fix error message when failing to detect filesystem

If we looped through /etc/filesystems trying to mount with each
type and failed all options, we forget to actually raise an
error message.

* src/lxc/lxc_container.c: Raise error if unable to detect
  the filesystems. Also fix existing error message

src/lxc/lxc_container.c

@@ -725,7 +725,7 @@ retry:
                 continue;
 
             virReportSystemError(errno,
-                                 _("Failed to bind mount directory %s to %s"),
+                                 _("Failed to mount device %s to %s"),
                                  src, fs->dst);
             goto cleanup;
         }
@@ -746,6 +746,12 @@ retry:
         goto retry;
     }
 
+    if (ret != 0) {
+        virReportSystemError(ENODEV,
+                             _("Failed to mount device %s to %s, unable to detect filesystem"),
+                             src, fs->dst);
+    }
+
     VIR_DEBUG("Done mounting filesystem ret=%d tryProc=%d", ret, tryProc);
 
 cleanup: