crypto: qat - remove unused PFVF stubs

The functions adf_enable_pf2vf_interrupts(), adf_flush_vf_wq() and
adf_disable_pf2vf_interrupts() are not referenced when the driver is
compiled with CONFIG_PCI_IOV=n. This patch removes these unused stubs.

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