edac_core: Do a better job with node removal

Make sure we remove groups at the right order

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 6b7e723..b10b45cc 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -207,6 +207,7 @@
 	}
 
 	mci->op_state = OP_ALLOC;
+	INIT_LIST_HEAD(&mci->grp_kobj_list);
 
 	/*
 	 * Initialize the 'root' kobj for the edac_mc controller