Bluetooth: Require streaming mode when it is requested for a socket

The L2CAP specification has two ways to support streaming mode: Allow
fallback to ERTM or basic mode when the remote device requests one of
those modes, or make the connection fail unless both sides agree on
streaming mode.

The current code does not properly support either method.  This change
makes a streaming mode connection fail if the remote device does not
also request streaming mode.

CRs-fixed: 336291
Change-Id: Id26f963a5e15d18e85a2faf2f8f01848e2a73fa4
Signed-off-by: Mat Martineau <mathewm@codeaurora.org>