ATT_OP_READ_BY_TYPE_REQUEST may return more than one char description
per response packet. Due to a missing offset adjustment we only ever
read the first description. Subsequent description were read by
issuing a new READ_BY_TYPE request. This is very inefficient as
at worst 3 times as many requests had to be send to the device.

Change-Id: I83ca75a42425fe230926411f068112865c249061
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>