crypto: cavium - Limit result reading attempts

commit c782a8c43e94ba6c09e9de2d69b5e3a5840ce61c upstream.

After issuing a request an endless loop was used to read the
completion state from memory which is asynchronously updated
by the ZIP coprocessor.

Add an upper bound to the retry attempts to prevent a CPU getting stuck
forever in case of an error. Additionally, add a read memory barrier
and a small delay between the reading attempts.

Signed-off-by: Jan Glauber <jglauber@cavium.com>
Reviewed-by: Robert Richter <rrichter@cavium.com>
Cc: stable <stable@vger.kernel.org> # 4.14
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>