octeontx2-af: fix VF bringup affecting PF promiscuous state

In the Linux kernel, the following vulnerability has been resolved: octeontx2-af: fix VF bringup affecting PF promiscuous state Mbox handling of nix_set_rx_mode for a VF with promiscuous and all_multi flags set to false causes deletion of the PF's promiscuous and allmulti MCAM rules. This occurs because the APIs that enable/disable these rules operate only on the PF, even when the mbox request is made via a VF interface. Guard both rvu_npc_enable_allmulti_entry() and rvu_npc_enable_promisc_entry() disable paths with an is_vf() check so that a VF bringing up or tearing down its interface cannot inadvertently clear the PF's MCAM rules.