virsh: Resolve Coverity NEGATIVE_RETURNS

Coverity notes that after we VIR_ALLOC_N(params, nparams) a failed call to
virDomainGetCPUStats could result in nparams being set to -1. In that case,
the subsequent virTypedParamsFree in cleanup will pass -1 which isn't good.

Use the returned value as the number of stats to display in the loop as
it will be the value reported from the hypervisor and may be less than
nparams which is OK
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

tools/virsh-domain.c

@@ -6734,7 +6734,7 @@ cmdCPUStats(vshControl *ctl, const vshCmd *cmd)
 {
     virDomainPtr dom;
     virTypedParameterPtr params = NULL;
-    int pos, max_id, cpu = 0, show_count = -1, nparams = 0;
+    int pos, max_id, cpu = 0, show_count = -1, nparams = 0, stats_per_cpu;
     size_t i, j;
     bool show_total = false, show_per_cpu = false;
     unsigned int flags = 0;
@@ -6853,11 +6853,12 @@ cmdCPUStats(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;
 
     /* passing start_cpu == -1 gives us domain's total status */
-    if ((nparams = virDomainGetCPUStats(dom, params, nparams, -1, 1, flags)) < 0)
+    if ((stats_per_cpu = virDomainGetCPUStats(dom, params, nparams,
+                                              -1, 1, flags)) < 0)
         goto failed_stats;
 
     vshPrint(ctl, _("Total:\n"));
-    for (i = 0; i < nparams; i++) {
+    for (i = 0; i < stats_per_cpu; i++) {
         vshPrint(ctl, "\t%-12s ", params[i].field);
         if ((STREQ(params[i].field, VIR_DOMAIN_CPU_STATS_CPUTIME) ||
              STREQ(params[i].field, VIR_DOMAIN_CPU_STATS_USERTIME) ||