crushtool: set type 0 name "device" for --build option

The crushmap built by crushtool cannot be used directly as the name of type 0 is not specified.
We may decompile the crushmap(it will automatically add type 0) and then recompile it to make it usable, but that's extra effort.

Signed-off-by: Sangdi Xu <xu.sangdi@h3c.com>

src/tools/crushtool.cc

@@ -617,6 +617,7 @@ int main(int argc, const char **argv)
       crush.set_item_name(i, "osd." + stringify(i));
     }
 
+    crush.set_type_name(0, "device");
     int type = 1;
     for (vector<layer_t>::iterator p = layers.begin(); p != layers.end(); ++p, type++) {
       layer_t &l = *p;