soc/intel/meteorlake: Make use of is_devfn_enabled() function

1. Replace all pcidev_path_on_root() and is_dev_enabled()
functions combination with is_devfn_enabled().
2. Remove unused local variable of device structure type
(struct device *).
3. Replace pcidev_path_on_root() and dev->enabled check with
is_devfn_enabled() call.

TEST=Able to build and boot without any regression seen on MTL.

Port of 'commit 50134eccbdf4 ("soc/intel/alderlake: Make use
of is_devfn_enabled() function")'

Signed-off-by: Dinesh Gehlot <digehlot@google.com>
Change-Id: I54bbd2bdba69a19e0559738035916fa7ac60faaa
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71161
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>
diff --git a/src/soc/intel/meteorlake/acpi.c b/src/soc/intel/meteorlake/acpi.c
index 66e6384..c049d07 100644
--- a/src/soc/intel/meteorlake/acpi.c
+++ b/src/soc/intel/meteorlake/acpi.c
@@ -175,13 +175,12 @@
 static unsigned long soc_fill_dmar(unsigned long current)
 {
 	unsigned long tmp;
-	const struct device *const igfx_dev = pcidev_path_on_root(PCI_DEVFN_IGD);
 	const uint64_t gfxvtbar = MCHBAR64(GFXVTBAR) & VTBAR_MASK;
 	const bool gfxvten = MCHBAR32(GFXVTBAR) & VTBAR_ENABLED;
 
 	printk(BIOS_DEBUG, "%s - gfxvtbar:0x%llx  0x%x\n",
 		__func__, gfxvtbar, MCHBAR32(GFXVTBAR));
-	if (is_dev_enabled(igfx_dev) && gfxvtbar && gfxvten) {
+	if (is_devfn_enabled(PCI_DEVFN_IGD) && gfxvtbar && gfxvten) {
 		tmp = current;
 		current += acpi_create_dmar_drhd(current, 0, 0, gfxvtbar);
 		current += acpi_create_dmar_ds_pci(current, 0, PCI_DEV_SLOT_IGD, 0);
@@ -201,7 +200,7 @@
 	acpi_dmar_drhd_fixup(tmp, current);
 
 	/* Add RMRR entry */
-	if (is_dev_enabled(igfx_dev) && gfxvtbar && gfxvten) {
+	if (is_devfn_enabled(PCI_DEVFN_IGD) && gfxvtbar && gfxvten) {
 		tmp = current;
 		current += acpi_create_dmar_rmrr(current, 0,
 				sa_get_gsm_base(), sa_get_tolud_base() - 1);