Adjusted memory usage in puny benchmarks

Reduced memory usage of puny benchmarks to
reduce the probability of ooming when tests
are run multiple times.

BUG=chromium-os:39629
TEST=./run_remote_tests.sh --use_emerged --board=$B --remote=$IP \
			kernel_fs_Punybench/control.daily

Change-Id: I83c7e88388e0ac58879ea366867aa335273b8304
Reviewed-on: https://gerrit.chromium.org/gerrit/45432
Tested-by: Paul Taysom <taysom@chromium.org>
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
Commit-Queue: Paul Taysom <taysom@chromium.org>
4 files changed