Bluetooth: doc: Fix displacement of L2CAP channel states description

Improves placement of channel states value description in Bluetooth API
documentation by moving to separate line proper comment describing
the value meaning.

Change-Id: Ib111884bd4a52bdb023b872598a852fc441fefe5
Signed-off-by: Arkadiusz Lichwa <arkadiusz.lichwa@tieto.com>