hw/acpi/ich9: clear smi_en on reset

Otherwise on reboot firmware might think (due to APMC_EN remaining set
from the previous boot) that SMI support is absent.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-trivial@nongnu.org
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/acpi/ich9.c

diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
index f04f6dc..8da5a2d 100644
--- a/hw/acpi/ich9.c
+++ b/hw/acpi/ich9.c
@@ -221,6 +221,7 @@
     acpi_pm_tmr_reset(&pm->acpi_regs);
     acpi_gpe_reset(&pm->acpi_regs);
 
+    pm->smi_en = 0;
     if (!pm->smm_enabled) {
         /* Mark SMM as already inited to prevent SMM from running. KVM does not
          * support SMM mode. */