drivers/staging: Removed unnecessary check for LUSTRE_VERSION_CODE

Given that this code is now part of the kernel tree, the #ifdef directive comparing LUSTRE_VERSION_CODE to the kernel version is no longer needed.

As a side effect, this will also remove the sparse error "directive in argument list".

Signed-off-by: Filipe Gonçalves <filipe@codinghighway.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>