Currently the PS/2 controller command KBD_CCMD_MOUSE_DISABLE
doesn't disable the PS/2 mouse communication at all, and the
PS/2 controller commands KBD_CCMD_KBD_DISABLE and
KBD_CCMD_KBD_ENABLE only disable and enable the keyboard
interrupt, which is very different from what a real PS/2
controller does. A guest may notice the difference.

Mask out pending data on disabled queues to correctly disable
the PS/2 controller communication.

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-Id: <20210525181441.27768-10-vr_qemu@t-online.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>