fixed nbnxn no LJ comb.rule AVX256 PME kernel

The nbnxn 2x(N+N) kernels did incorrect LJ parameter lookups
for systems which do not follow LJ combination rules.
The kernels are only used with AVX256 with Ewald type electrostatics.

Change-Id: I6ccc133e7f21a43c25cf61d7ede43da7889e66de
Merge "fixed nbnxn no LJ comb.rule AVX256 PME kernel" into release-4-6