chardev/wctable: don't free the instance in wctablet_chr_finalize

chardev/wctable: don't free the instance in wctablet_chr_finalize

Object is supposed to be freed by invoking obj->free, and not
obj->instance_finalize. This would lead to use-after-free followed by
double free in object_unref/object_finalize.

Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20211117142349.836279-1-d-tatianin@yandex-team.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit fdc6e168181d06391711171b7c409b34f2981ced)
Signed-off-by: Michael Roth <michael.roth@amd.com>