port: reset peer delay filter in port_nrate_initialize()

Prior to this change, peer delay calculation after asCapable
became TRUE was affected by the values accumulated by the filter
during the last period in which asCapable was TRUE.

Signed-off-by: Delio Brignoli <dbrignoli@audioscience.com>
Merge branch 'asi1230-upstream-tracking' into asi1230-master