tests: benchmarks: sys_kernel: Enable benchmark for slower SoCs

Few SoCs whose clock speed is very less will cause multiple ticks
to occur for 1 sec of sleep. For such a platform we cant run
the loops for over 5000 because the tick handler will get executed.
Thus rendering the test useless for such platforms. By reducing
the number of iterations we get the required benchmark results.

Fixes: GH-7906

Signed-off-by: Adithya Baglody <adithya.nagaraj.baglody@intel.com>