crypto: qat - add bank state save and restore for qat_420xx

crypto: qat - add bank state save and restore for qat_420xx

Register the functions required to save and restore the state of a ring
bank on the qat_420xx device.  Since this logic is shared across QAT
GEN4 devices, reuse the existing GEN4 implementation.

This functionality enables saving and restoring the state of a Virtual
Function (VF), which is required for supporting VM Live Migration.

Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: Ahsan Atta <ahsan.atta@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>