[S390] pm: con3270 power management callbacks.

Introduce the power management callbacks to the 3270 driver. On suspend
the current 3270 view is deactivated and for non-console 3270 device
the release callback is done. This disconnects the current tty /
fullscreen application from the 3270 device. On resume the current
view is reactivated, on the tty you get a fresh login.
If the system panics before the 3270 device has been resumed, the ccw
device for the 3270 console is reactivated with ccw_device_force_console.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>