Staging: vme: remove an unnecessary and wrong warning message

The wrong warning message in vme_user_probe() will mislead developers and
users. As the error message which prompt cdev_add() error already exists,
just remove the unnecessary and wrong message.

Signed-off-by: Navy Cheng <navych@126.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>