qemu: cleanup code to relece SPICE ports

qemu: cleanup code to relece SPICE ports

SPICE ports cleanup looks overly complicated. We can just set *reserved
flags whenever port is reserved (auto or non auto).

Also *Reserved flags are not cleared on stop in case of reconnect with
autoport (flags are set on reconnect in qemuProcessGraphicsReservePorts
call). Yeah config is freed in the end of stopping domain but still.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy@openvz.org>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>