Restoring localWorkSize to original values.
Issue #86

Reviewed by: Andre Loureiro

On FluidDynamics, Ising, Mandelbrot, PathIntegrals and XY demos the
localWorkSize parameter was being used as null, now it is restored and
handled properly to CPU and GPU devices.

Signed-off-by: Marcelo Morais <m.morais@samsung.com>