crypto: qat - fix wording and formatting in code comment

Remove an unintentional extra space and improve the readability of a
PFVF related code comment.

Signed-off-by: Marco Chiappero <marco.chiappero@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>