Disabled heartwall benchmark on CPU

Unfourtunately the heartwall benchmark is not suitable to be run on the
CPU platform of the odroid, since even with the minimum available number
of threads we receive an CL_OUT_OF_HOST_MEMORY caused by the argument
passed to the kernel being too big.

We leave the GPU benchmark enabled to make comparisons with the x86
platform.

Makefile

@@ -44,7 +44,6 @@ OPENCL_BENCHMARK_CPU:
 	./time-and-save.sh opencl/particlefilter times.dat cpu
 	./time-and-save.sh opencl/gaussian times.dat cpu
 	./time-and-save.sh opencl/nn times.dat cpu
-	./time-and-save.sh opencl/heartwall times.dat cpu
 	./time-and-save.sh opencl/hybridsort times.dat cpu
 	./time-and-save.sh opencl/dwt2d times.dat cpu