mb/starlabs/lite: Reset XHCI before entering S5

Reset the XHCI controller prior to S5 to avoid XHCI preventing shutdown.
Linux needs to put the XHCI into D3 before shutting down but the
powerstate commands do not perform a reset.

Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Change-Id: I3be70443eb85a7dff8055c9de0ca2fd89f4fc88d
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67678
Reviewed-by: Tim Wawrzynczak <inforichland@gmail.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/starlabs/lite/smihandler.c

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <acpi/acpi.h>
+#include <cpu/x86/smm.h>
+#include <intelblocks/xhci.h>
+
+void mainboard_smi_sleep(u8 slp_typ)
+{
+	/*
+	 * Workaround: Reset the XHCI controller prior to S5 to avoid
+	 * XHCI preventing shutdown. Linux needs to put the XHCI into D3
+	 * before shutting down but the powerstate commands do not
+	 * perform a reset.
+	 */
+	if (slp_typ == ACPI_S5)
+		xhci_host_reset();
+}