crypto: qat - extend scope of lock in adf_cfg_add_key_value_param()

The function adf_cfg_add_key_value_param() attempts to access and modify
the key value store of the driver without locking.

Extend the scope of cfg->lock to avoid a potential race condition.

Fixes: 92bf269f ("crypto: qat - change behaviour of adf_cfg_add_key_value_param()")
Signed-off-by: Nivas Varadharajan Mugunthakumar <nivasx.varadharajan.mugunthakumar@intel.com>
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>