kvm: x86: only channel 0 of the i8254 is linked to the HPET

commit e5e57e7a upstream.

While setting the KVM PIT counters in 'kvm_pit_load_count', if
'hpet_legacy_start' is set, the function disables the timer on
channel[0], instead of the respective index 'channel'. This is
because channels 1-3 are not linked to the HPET.  Fix the caller
to only activate the special HPET processing for channel 0.

Reported-by: P J P <pjp@fedoraproject.org>
Fixes: 0185604c
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
(cherry picked from commit ef90cf3d)
Signed-off-by: Willy Tarreau <w@1wt.eu>