Depending on specifics, some 'serdev' devices might need prevent
parent console device from being removed and corresponding memory
deallocated to properly function until the very end of Barebox's
execution. An example of such a use-case would be a reset handler
relying on a serdev device for transport.

To avoid having to develop complicatione reference counting/ownership
scheme drop all of the code that calls console_unregister() and frees
the memory effectively making the problem above impossible to arise.

All of the de-initialization that serial drivers were doing in their
.remove functions was somewhat superflous anyway, so this change
should be pretty harmless.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>