hw/char/mcf_uart: QOMify the ColdFire UART

Use type_init() etc. to adapt the ColdFire UART
to the latest QEMU device conventions.

Signed-off-by: Thomas Huth <huth@tuxfamily.org>
Message-Id: <1485586582-6490-1-git-send-email-huth@tuxfamily.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>