Bluetooth: btsdio: Do not bind to non-removable BCM4356

BCM4356 devices soldered onto the PCB (non-removable) use an UART
connection for bluetooth, such as the Rock960, but it also advertise
btsdio support as a sdio function.

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
CC: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>