Bluetooth: Fix potential NULL dereference in RFCOMM bind callback

[ Upstream commit 951b6a0717db97ce420547222647bcc40bf1eacd ]

addr can be NULL and it should not be dereferenced before NULL checking.

Signed-off-by: Jaganath Kanakkassery <jaganath.k@samsung.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>