ppc440: Rename parent field of PPC460EXPCIEState to match code style

QOM prefers to call the parent field parent_obj, change
PPC460EXPCIEState ro match that convention.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <6995f28215d2a489a661b7d91a1783048829d467.1688586835.git.balaton@eik.bme.hu>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

hw/ppc/ppc440_uc.c

@@ -774,7 +774,7 @@ void ppc4xx_dma_init(CPUPPCState *env, int dcr_base)
 OBJECT_DECLARE_SIMPLE_TYPE(PPC460EXPCIEState, PPC460EX_PCIE_HOST)
 
 struct PPC460EXPCIEState {
-    PCIExpressHost host;
+    PCIExpressHost parent_obj;
 
     MemoryRegion iomem;
     qemu_irq irq[4];