vshReadlineOptionsGenerator: Add already provided VSH_OT_ARGV options to list

It's helpful for users while they type certain kind of VSH_OT_ARGV options.
e.g.

$ virsh domstats --domain sles12sp3 --d<TAB>
Signed-off-by: NLin Ma <lma@suse.com>

tools/vsh.c

@@ -2685,7 +2685,7 @@ vshReadlineOptionsGenerator(const char *text,
         }
 
         while (opt) {
-            if (STREQ(opt->def->name, name)) {
+            if (STREQ(opt->def->name, name) && opt->def->type != VSH_OT_ARGV) {
                 exists = true;
                 break;
             }