soc/intel/apl: Hide PMC/IPC ACPI device from Windows

No drivers are needed/available, so hide the device to prevent
an unknown device from showing under Device Manager.
Linux does not use the ACPI _STA so no effect there.

Change-Id: I02efb64a845edc6e4fc559e7e99a7825abf4c2aa
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/74892
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: CoolStar <coolstarorganization@gmail.com>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/soc/intel/apollolake/acpi/pmc_ipc.asl

@@ -42,5 +42,9 @@ scope (\_SB) {
 
 			Return (^RBUF)
 		}
+		Method (_STA, 0x0, NotSerialized)
+		{
+			Return(0xb)
+		}
 	}
 }