event/sw: fix events mis-identified as needing reorder

event/sw: fix events mis-identified as needing reorder

When taking events from a port, we checked the history list to check if the
event needed to be put back in order i.e. originally came from a reordered
queue type. The check for reordering involved checking if the reorder
buffer entry pointer was null. However, after that pointer was used it was
never cleared to null again.

This caused problems when we had mixed reordered and atomic or parallel
events, as the events from the latter two queue types were misidentified as
needing reordering. This let in some cases to crashes, but mostly led to
dropping events, and then application lock-up.

Fixes: 617995dfc5b2 ("event/sw: add scheduling logic")

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Harry van Haaren <harry.van.haaren@intel.com>