Bluetooth: Reject SCO when hci connection timeouts

This patch sends Reject Synchronous Connection Request Command when
hci_conn_timeout is triggered, and the SCO connection is in BT_CONNECT2
state. It prevents inconsistency if the remote host doesn't implement
properly the timeout for the connection request, and it removes the
connection reference left when the socket is closed for incoming SCO
connections.

[ 2650.129080] sco_sock_release: sock ffff8801ca417400, sk ffff88020c408800
[ 2650.129092] sco_sock_clear_timer: sock ffff88020c408800 state 6
[ 2650.129101] __sco_sock_close: sk ffff88020c408800 state 6 socket
	ffff8801ca417400
[ 2650.129108] sco_chan_del: sk ffff88020c408800, conn ffff8801c650ea20,
	err 104
[ 2650.129114] hci_conn_put: hcon ffff88020c40a800 orig refcnt 1
[ 2650.129128] sco_sock_kill: sk ffff88020c408800 state 9
[ 2650.129135] sco_sock_destruct: sk ffff88020c408800
[ 2650.138468] hci_conn_timeout: hcon ffff88020c40a800 state BT_CONNECT2

Signed-off-by: Claudio Takahasi <claudio.takahasi@openbossa.org>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@openbossa.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>