Convert 3215 console driver to new channel subsystem driver

this adds support for the driver model to the 3215 driver. The console
is one of the biggest problems because the regular device detection
is now done at initcall time although we actually want full
support for channel attached console devices as early as possible.
con3215_init() now uses a special ccw_device_probe_console() function
to do an early initialization of a single device.

The main backdraw for users is that the console can no longer
be autodetected when not running under VM. LPAR or P390 users
with a channel attached console now have to specify
console_device=f00 as a kernel parameter.

Authors:
	Martin Schwidefsky <schwidefsky@de.ibm.com>
	Arnd Bergmann <arndb@de.ibm.com>