PCI: Use PCI_STD_NUM_BARS instead of 6

pci_read_bases() is given literal 6 that means PCI_STD_NUM_BARS.  Replace
the literal with the define to annotate the code better.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Link: https://patch.msgid.link/20250416100239.6958-1-ilpo.jarvinen@linux.intel.com

Author: ij-intel

drivers/pci/probe.c

@@ -2058,7 +2058,7 @@ int pci_setup_device(struct pci_dev *dev)
 		if (class == PCI_CLASS_BRIDGE_PCI)
 			goto bad;
 		pci_read_irq(dev);
-		pci_read_bases(dev, 6, PCI_ROM_ADDRESS);
+		pci_read_bases(dev, PCI_STD_NUM_BARS, PCI_ROM_ADDRESS);
 
 		pci_subsystem_ids(dev, &dev->subsystem_vendor, &dev->subsystem_device);