eatt: Improve handling incoming EATT connection

With this patch we make sure that eatt_dev is created always when EATT
is supported on the peer side, no matter what is the connection role.

It will allow to accept ecoc channels when Android device is peripheral
device

Bug: 159786353
Bug: 191313013
Tag: #feature
Test: atest --host net_test_eatt
Sponsor: jpawlowski@
Merged-In: I4d735bc4a2d74f637e9c7f7819e10659af9b0fbb
Change-Id: I4d735bc4a2d74f637e9c7f7819e10659af9b0fbb