Fix GATT over BREDR not connecting

For BREDR connections, the upper stack always sends the request with
transport type DUMO, and this should be treated as BREDR if the device
is not known as LE only.

Bug: 62387078
Test: pts GattOverBrEdrTest
Change-Id: I726252e85e78bff2c9585332d2748a0d92a9f6d3