staging: keucr: remove driver

The driver hasn't been fully cleaned up and it doesn't look like anyone
is working on it anymore (including the original author). So remove the
driver and all references to it. If someone wants to finish cleaning
the driver up and moving it out of staging, this commit can be reverted.

Signed-off-by: Kristina Martšenko <kristina.martsenko@gmail.com>
Cc: Cho, Yu-Chen <acho@novell.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>