Remove delays

A new PR IN or PR OUT command is only submitted after the previous
command has finished, so a conformant target must be able to pass
the entire test suite without any delays.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Add tearDown() methods

Make sure that any registered PR keys get unregistered if a test fails.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Do not start the tests if reading fails

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Unregister PR keys before starting any tests

Clean up any PR keys left from a previous run before starting the tests.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Compute device nodes from env var PGR_VALIDATE_SN

Signed-off-by: Bart Van Assche <bvanassche@acm.org>