Bluetooth: Fix bt_sock_recvmsg when MSG_TRUNC is not set

Bluetooth: Fix bt_sock_recvmsg when MSG_TRUNC is not set

Commit 7e0be40f8c327d718d700d1373b4be7f75135065 attempt to introduce
proper handling for MSG_TRUNC but recv and variants should still work
as read if no flag is passed, but because the code may set MSG_TRUNC to
msg->msg_flags that shall not be used as it may cause it to be behave as
if MSG_TRUNC is always, so instead of using it this changes the code to
use the flags parameter which shall contain the original flags.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>