linux-testing: Fix build with default config.

Regression introduced by 03a3a905.

Our default config includes all modules and since torvalds/linux@47ca6ec
this results in a regression due to in a circular dependency between
libcfs and LNet:

depmod: ERROR: Found 2 modules in dependency cycles!
depmod: ERROR: Cycle detected: lnet -> libcfs -> lnet

The discussion regarding this in the LKML is here:

https://lkml.org/lkml/2015/11/2/388

So this adds a patch which is not yet included in mainline and has been
submitted to the LKML at:

https://lkml.org/lkml/2015/11/6/987



Built successfully via "nix-build -A linux-testing".

Signed-off-by: aszlig <aszlig@redmoonstudios.org>