soc/amd/stoneyridge/acpi/northbridge: drop _STA method from PCI0 scope

The PCI root complex itself isn't on an enumerable bus, so without
providing an _STA method, the device will still be assumed to be present
and visible, so this won't change behavior. This also brings Stoneyridge
more in line with the newer SoCs.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I663c7bcba89ffe25d0819d83461cb95e10f49028
Reviewed-on: https://review.coreboot.org/c/coreboot/+/75671
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/stoneyridge/acpi/northbridge.asl

@@ -11,11 +11,6 @@ Method(_BBN, 0, NotSerialized)	/* Bus number = 0 */
 	Return(0)
 }
 
-Method(_STA, 0, NotSerialized)
-{
-	Return(0x0F)	/* Status is visible */
-}
-
 Method(_PRT,0, NotSerialized)
 {
 	If(PICM)