soc/intel: Replace uses of dev_find_slot()

To call dev_find_slot(0, xx) in romstage can produce
invalid results since PCI bus enumeration has not
been progressed yet.

Replace this with method that relies on bus topology
that walks the root bus only.

Change-Id: I2883610059bb9fa860bba01179e7d5c58cae00e5
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33996
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/soc/intel/broadwell/acpi.c b/src/soc/intel/broadwell/acpi.c
index e51c9bf..25867c5 100644
--- a/src/soc/intel/broadwell/acpi.c
+++ b/src/soc/intel/broadwell/acpi.c
@@ -580,7 +580,7 @@
 
 static unsigned long acpi_fill_dmar(unsigned long current)
 {
-	struct device *const igfx_dev = dev_find_slot(0, SA_DEVFN_IGD);
+	struct device *const igfx_dev = pcidev_path_on_root(SA_DEVFN_IGD);
 	const u32 gfxvtbar = MCHBAR32(GFXVTBAR) & ~0xfff;
 	const u32 vtvc0bar = MCHBAR32(VTVC0BAR) & ~0xfff;
 	const bool gfxvten = MCHBAR32(GFXVTBAR) & 0x1;