Bluetooth: Host: Fix handling of incomplete data status adv reports

When receiving extended advertising reports with incomplete
data status, it is not necessary to mark for recovering from
currently assembled fragments, but rather drop them and
start a fresh assembly of subsequently received extended
advertising reports.

Timing changes in the Controller cause Periodic Advertising
PDUs AUX_SYNC_IND + AUX_CHAIN_IND to be placed between
primary channel ADV_EXT_IND and AUX_ADV_IND. This causes the
Controller to generate alternating incomplete and complete
data status reports, exposing the Host bug that is fixed in
this commit.

Relates to commit ba09a252 ("bluetooth: host: refactor
bt_hci_le_per_adv_report data reassembly").

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>