nimble/ll: Fix error code in read remote feature event
nimble/ll: Fix error code in read remote feature event

If connection is dropped and read remote feature was in progress let us
send this event before disconnection complete event and with actually
error code and not the fixed one as it was so far.

This should fixed certification test LL/CONN/MAS/BV-19

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