nimble/ll: Fix calculating auxiliary offset in AUX_ADV_IND
nimble/ll: Fix calculating auxiliary offset in AUX_ADV_IND

The auxiliary offset should be calculated as time difference between
current packet and auxiliary packet as set in scheduler. This gives
precise time so there's no need for magic "plus ones" anymore.

X-Original-Commit: f84a0f64ecbfc921fa1fb165c2f613a8d2392ef0

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble