nimble/ll: Fix legacy extended directed advertising event length
nimble/ll: Fix legacy extended directed advertising event length

Directed address is already within `struct ble_ll_ext_adv_report' so
there is no need to increase `evt->event_len`

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