crypto: qat - remove unnecessary list iteration

There's no need to iterate through the list for instances in the
accel_table since the number of devices is already known in this file.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>