op-test: Fix exit_code
op-test: Fix exit_code

Set the exit_code for test errors and test failures so the proper
exit_code is returned upon exit (the newly added finally clause runs
which needs to pick up the proper exit_code in case exceptions are
thrown during the test runs).

Signed-off-by: Deb McLemore <1938e6bc52a6fb400ff401d42bc5360c2c7aaa30@linux.ibm.com>

open-power/op-test-framework,open-power/op-test-framework,open-power/op-test-framework