ftests: Add an lssubsys -a functional test

ftests: Add an lssubsys -a functional test

Add a functional test that exercises 'lssubsys -a'

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Test Results:
        Run Date:                          Mar 24 19:12:33
        Passed:                                  1 test(s)
        Skipped:                                 0 test(s)
        Failed:                                  0 test(s)
-----------------------------------------------------------------
Timing Results:
        Test                                    Time (sec)
        ---------------------------------------------------------
        setup                                        20.06
        030-lssubsys-lssubsys_all.py                  0.18
        teardown                                      0.00
        ---------------------------------------------------------
        Total Run Time                               20.23

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>