crypto: qat - add shutdown handler to qat_420xx

crypto: qat - add shutdown handler to qat_420xx

During a warm reset via kexec, the system bypasses the driver removal
sequence, meaning that the remove() callback is not invoked.
If a QAT device is not shutdown properly, the device driver will fail to
load in a newly rebooted kernel.

This might result in output like the following after the kexec reboot:

    420xx 0000:01:00.0: Failed to power up the device
    420xx 0000:01:00.0: Failed to initialize device
    420xx 0000:01:00.0: Resetting device qat_dev0
    420xx 0000:01:00.0: probe with driver 420xx failed with error -14

Implement the shutdown() handler that hooks into the reboot notifier
list. This brings down the QAT device and ensures it is shut down
properly.

Cc: <stable@vger.kernel.org>
Fixes: fcf60f4bcf54 ("crypto: qat - add support for 420xx devices")
Reviewed-by: Ahsan Atta <ahsan.atta@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>