security_selinux: Use proper structure to access socket data

In virSecuritySELinuxSetSecurityChardevLabel() we are labelling unix
socket path, but accessing another structure of the union.  This does
not pose a problem currently as both paths are at the same offset, but
this should be fixed for the future.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

src/security/security_selinux.c

@@ -1740,7 +1740,7 @@ virSecuritySELinuxSetSecurityChardevLabel(virDomainDefPtr def,
 
     case VIR_DOMAIN_CHR_TYPE_UNIX:
         if (!dev_source->data.nix.listen) {
-            if (virSecuritySELinuxSetFilecon(dev_source->data.file.path,
+            if (virSecuritySELinuxSetFilecon(dev_source->data.nix.path,
                                              imagelabel) < 0)
                 goto done;
         }