nb/intel/x4x: Define and use HOST_BRIDGE macro

Other Intel northbridges do this.

Tested with BUILD_TIMELESS=1, Asus P5QL PRO does not change

Change-Id: I50785b7bf3e3cc0eade7fda4b4b2e2bb71a54c31
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44143
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/northbridge/intel/x4x/bootblock.c

@@ -13,5 +13,5 @@ void bootblock_early_northbridge_init(void)
 	reg32 = TPM32(0);
 
 	reg32 = CONFIG_MMCONF_BASE_ADDRESS | 16 | 1;
-	pci_io_write_config32(PCI_DEV(0, 0, 0), D0F0_PCIEXBAR_LO, reg32);
+	pci_io_write_config32(HOST_BRIDGE, D0F0_PCIEXBAR_LO, reg32);
 }