Input: i8042 - restore control register when enabling port fails

When enabling interrupts for a port fails, the interrupt enable and
port enable bits remain set in i8042_ctr. Later writes of i8042_ctr
to the hardware could accidentally retry enabling interrupts. Clear
the bits on failure.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>