Enable possiblity to configure and build this driver.
Signed-off-by: NFrank Haverkamp <haver@linux.vnet.ibm.com>
Co-authors: Joerg-Stephan Vogt <jsvogt@de.ibm.com>,
            Michael Jung <MIJUNG@de.ibm.com>,
            Michael Ruettger <michael@ibmra.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>