virsh: Simplify control flow for 'desc' command

Just like the commit 8941c800, It does the similar thing.
Signed-off-by: NLin Ma <lma@suse.com>

tools/virsh-domain.c

@@ -8330,7 +8330,6 @@ cmdDesc(vshControl *ctl, const vshCmd *cmd)
     char *tmpstr;
     const vshCmdOpt *opt = NULL;
     virBuffer buf = VIR_BUFFER_INITIALIZER;
-    bool pad = false;
     bool ret = false;
     unsigned int flags = VIR_DOMAIN_AFFECT_CURRENT;
 
@@ -8348,18 +8347,16 @@ cmdDesc(vshControl *ctl, const vshCmd *cmd)
     if ((state = virshDomainState(ctl, dom, NULL)) < 0)
         goto cleanup;
 
-    while ((opt = vshCommandOptArgv(ctl, cmd, opt))) {
-        if (pad)
-            virBufferAddChar(&buf, ' ');
-        pad = true;
-        virBufferAdd(&buf, opt->data, -1);
-    }
-
     if (title)
         type = VIR_DOMAIN_METADATA_TITLE;
     else
         type = VIR_DOMAIN_METADATA_DESCRIPTION;
 
+    while ((opt = vshCommandOptArgv(ctl, cmd, opt)))
+        virBufferAsprintf(&buf, "%s ", opt->data);
+
+    virBufferTrim(&buf, " ", -1);
+
     if (virBufferError(&buf)) {
         vshError(ctl, "%s", _("Failed to collect new description/title"));
         goto cleanup;