vz: Fix invalid iteration of def->cputune.vcpupin

The array doesn't necessarily have the same cardinality as the count of
vCPUs for a domain. Iterating it can cause access beyond the end of the
array.

src/vz/vz_sdk.c

@@ -1958,7 +1958,7 @@ prlsdkCheckUnsupportedParams(PRL_HANDLE sdkdom, virDomainDefPtr def)
     }
 
     if (def->cputune.vcpupin) {
-        for (i = 0; i < virDomainDefGetVcpus(def); i++) {
+        for (i = 0; i < def->cputune.nvcpupin; i++) {
             if (!virBitmapEqual(def->cpumask,
                                 def->cputune.vcpupin[i]->cpumask)) {
                 virReportError(VIR_ERR_CONFIG_UNSUPPORTED,