### Fix undefined timestamp for NORD field

When monitoring non-val fields such as `NORD` for several record types updates
are not sent out correctly resulting in incorrect timestamps. This fixes this
for the record types `aai`, `aao`, `subArray`.

Note that support modules that already implement this in the device support
layer will need to be updated to avoid doubled monitor updates. If those modules
are to be built against older versions of EPICS base then they will need to use
the defined macros `AAO_POSTS_NORD`, `AAI_POSTS_NORD`, `SA_POSTS_NORD`, or
`WF_POSTS_NORD` as appropriate to detect this change.