soc/amd/picasso: fix host bridge bus numbers

The host bridge's resources covering bus numbers assumed
256 buses were being decoded. However, MMCONFIG was only
covering 64 buses. This results in Linux complaining:

    acpi PNP0A08:00: [Firmware Info]: MMCONFIG for domain 0000
    [bus 00-3f] only partially covers this bridge

When retrieving the host bridge's resources fix up the
bus numbers to utilize MMCONF_BUS_NUMBER Kconfig. I couldn't
keep IASL from complaining when trying to do this statically.

BUG=b:158874061

Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Change-Id: Ief1901743e2c99f583ef0181490d493d23734f64
Reviewed-on: https://review.coreboot.org/c/coreboot/+/42734
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
diff --git a/src/soc/amd/picasso/acpi/sb_pci0_fch.asl b/src/soc/amd/picasso/acpi/sb_pci0_fch.asl
index 27c4661..7488b55 100644
--- a/src/soc/amd/picasso/acpi/sb_pci0_fch.asl
+++ b/src/soc/amd/picasso/acpi/sb_pci0_fch.asl
@@ -101,6 +101,11 @@
 	Subtract(Local0, TOM1, Local0)
 	Store(Local0, MM1L)
 
+	CreateWordField(CRES, ^PSB0._MAX, BMAX)
+	CreateWordField(CRES, ^PSB0._LEN, BLEN)
+	Store(CONFIG_MMCONF_BUS_NUMBER - 1, BMAX)
+	Store(CONFIG_MMCONF_BUS_NUMBER, BLEN)
+
 	Return(CRES) /* note to change the Name buffer */
 } /* end of Method(_SB.PCI0._CRS) */