nimble/ll: Fix scanner assert on receiving AUX_ADV_IND
nimble/ll: Fix scanner assert on receiving AUX_ADV_IND

If scanned chain was truncated due to low buffers for HCI event we may
be already too late to remove next AUX from scheduler and thus can
receive next packet. Just ignore PDU if truncated was already sent.

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