soc/intel/braswell: Adjust status of IOSF ACPI object

Neither Windows nor mainline Linux make use of IOSF on the Braswell
platform, so adjust the ACPI status return value based on
CONFIG(CHROMEOS) to prevent an unknown device being listed in Windows
device manager.

TEST=build/boot Win11, Linux 6.2 on google/edgar

Change-Id: Ic51624ffd816d48c007c13d510601cf8cbf1edc4
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/77142
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sean Rhodes <sean@starlabs.systems>

src/soc/intel/braswell/acpi/southcluster.asl

@@ -239,6 +239,15 @@ Device (IOSF)
 		RBAS = CONFIG_ECAM_MMCONF_BASE_ADDRESS + 0xD0
 		Return (^RBUF)
 	}
+
+	Method (_STA)
+	{
+#if CONFIG(CHROMEOS)
+		Return (0xF)
+#else
+		Return (0x0)
+#endif
+	}
 }
 
 /* LPC Bridge 0:1f.0 */