src/device: add IS_ENABLED() around Kconfig symbol references

Some of these can be changed from #if to if(), but that will happen
in a follow-on commmit.

Change-Id: I66cde1adcf373889b03f144793c0b4f46d21ca31
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/20338
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/device/pci_early.c

@@ -71,7 +71,7 @@ unsigned pci_find_capability(pci_devfn_t dev, unsigned cap)
 #endif /* __PRE_RAM__ */
 
 
-#if CONFIG_EARLY_PCI_BRIDGE
+#if IS_ENABLED(CONFIG_EARLY_PCI_BRIDGE)
 
 static void pci_bridge_reset_secondary(device_t p2p_bridge)
 {