w1: fix loop in w1_fini()

The __w1_remove_master_device() function calls:

	list_del(&dev->w1_master_entry);

So presumably this can cause an endless loop.

Fixes: 7785925d ("[PATCH] w1: cleanups.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>