spice-qemu-char: Drop hackish vmc_register on spice_chr_write

Now that the core takes care of fe_open tracking we no longer need this hack.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Message-id: 1364292483-16564-12-git-send-email-hdegoede@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
