soc: nrf53: Restore accidentally removed suppress_message flag check

This is a follow-up to commit 7195db01.

Restore the check that was accidentaliy removed in the above commit,
so that the message is again logged only once per detection of the
anomaly 160 conditions.

Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>