Bluetooth: Fix SCO connection reference

Bluetooth: Fix SCO connection reference

This patch fixes decrementing SCO connection reference right after
stablishing the SCO connection with defer setup enabled. The dump below
shows a disconnection command with handle 0, the connection is still in
BT_CONNECT2 state and there isn't a handle associated with it.

< HCI Command: Accept Synchronous Connection (0x01|0x0029) plen 21
  bdaddr 78:47:1D:B3:72:6C
> HCI Event: Command Status (0x0f) plen 4
  Accept Synchronous Connection (0x01|0x0029) status 0x00 ncmd 1
< HCI Command: Disconnect (0x01|0x0006) plen 3
  handle 0 reason 0x13
  Reason: Remote User Terminated Connection
> HCI Event: Command Status (0x0f) plen 4
  Disconnect (0x01|0x0006) status 0x00 ncmd 1
> HCI Event: Synchronous Connect Complete (0x2c) plen 17
  status 0x00 handle 46 bdaddr 78:47:1D:B3:72:6C
  type eSCO
  Air mode: CVSD
< SCO data: handle 46 flags 0x00 dlen 48

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>