i40e: fix potential NULL pointer dereferencing of pf->vf i40e_sync_vsi_filters()

[ Upstream commit 9525a3c3 ]

Add check for pf->vf not being NULL before dereferencing
pf->vf[vsi->vf_id] in updating VSI filter sync.
Add a similar check before dereferencing !pf->vf[vsi->vf_id].trusted
in the condition for clearing promisc mode bit.

Fixes: c87c938f

 ("i40e: Add VF VLAN pruning")
Signed-off-by: Andrii Staikov <andrii.staikov@intel.com>
Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>