OpTestReboot: add half-second delay to reboot
OpTestReboot: add half-second delay to reboot

.. so that we are sure that the reboot command arrives before our
attempt to grep the log for the fast reset message..

Signed-off-by: Klaus Heinrich Kiwi <d568b8cd7ef64877891488bb3328757d2d21c847@linux.vnet.ibm.com>

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