spi: unbinding slave before calling spi_destroy_queue

We make a mistake while backport 'commit 84855678add8 ("spi: Fix
controller unregister order")'. What we should do is call __unreigster
for each device before spi_destroy_queue. This problem exist in
linux-4.4.y/linux-4.9.y.

Signed-off-by: yangerkun <yangerkun@huawei.com>