kernel_fs_Punybench now uses args to select test

Because some of the tests are broken waiting for an upstream fix
and some of the tests run for several hours, the desired tests
have to be selected by passing a list of tests to in args.
Tests: --nop, --mem, --disk, --ecryptfs

BUG=chromium-os:34951
TEST=ran tests on amd64

Change-Id: I82b25d163ad77fa6c72aff39879b03442b07302d
Reviewed-on: https://gerrit.chromium.org/gerrit/34512
Reviewed-by: Scott Zawalski <scottz@chromium.org>
Commit-Ready: Paul Taysom <taysom@chromium.org>
Tested-by: Paul Taysom <taysom@chromium.org>
2 files changed