hw/pci/pci: Simplify pci_bar_address() using MACHINE_GET_CLASS() macro

Remove unnecessary intermediate variables.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/pci/pci.c

@@ -1446,9 +1446,7 @@ pcibus_t pci_bar_address(PCIDevice *d,
 {
     pcibus_t new_addr, last_addr;
     uint16_t cmd = pci_get_word(d->config + PCI_COMMAND);
-    Object *machine = qdev_get_machine();
-    ObjectClass *oc = object_get_class(machine);
-    MachineClass *mc = MACHINE_CLASS(oc);
+    MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
     bool allow_0_address = mc->pci_allow_0_address;
 
     if (type & PCI_BASE_ADDRESS_SPACE_IO) {