ocf-linux: remove extension and build out of tree

Remove the OCF linux kernel extension instead opting to build ocf-linux
modules out of tree.
This is easier for users since no kernel config tweaking is required.
On the downside the OCF drivers can't be used, but then all of the
kernel crypto drivers are available to users via cryptosoft which is
preferred.
Also remove it from the menu to utilize a virtual.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>