dm: mevent: remove useless vmname global variable

The vmname variable is missing 'export',
so it's probably only shadowing the already
exported variable from devicemodel/include/dm.h

Tracked-On: #1415
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>

Author: Tomas Winkler

devicemodel/include/mevent.h

@@ -36,7 +36,6 @@ enum ev_type {
 	EVF_SIGNAL		/* Not supported yet */
 };
 
-char *vmname;
 struct mevent;
 
 struct mevent *mevent_add(int fd, enum ev_type type,