wifi: iwlwifi: mvm: Add NULL check before dereferencing the pointer

While vif pointers are protected by the corresponding "*active"
fields, static checkers can get confused sometimes. Add an explicit
check.
Signed-off-by: Mukesh Sisodiya <mukesh.sisodiya@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230614154951.78749ae91fb5.Id3c05d13eeee6638f0930f750e93fb928d5c9dee@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/power.c

@@ -647,30 +647,32 @@ static void iwl_mvm_power_set_pm(struct iwl_mvm *mvm,
 		return;
 
 	/* enable PM on bss if bss stand alone */
-	if (vifs->bss_active && !vifs->p2p_active && !vifs->ap_active) {
+	if (bss_mvmvif && vifs->bss_active && !vifs->p2p_active &&
+	    !vifs->ap_active) {
 		bss_mvmvif->pm_enabled = true;
 		return;
 	}
 
 	/* enable PM on p2p if p2p stand alone */
-	if (vifs->p2p_active && !vifs->bss_active && !vifs->ap_active) {
+	if (p2p_mvmvif && vifs->p2p_active && !vifs->bss_active &&
+	    !vifs->ap_active) {
 		p2p_mvmvif->pm_enabled = true;
 		return;
 	}
 
-	if (vifs->bss_active && vifs->p2p_active)
+	if (p2p_mvmvif && bss_mvmvif && vifs->bss_active && vifs->p2p_active)
 		client_same_channel =
 			iwl_mvm_have_links_same_channel(bss_mvmvif, p2p_mvmvif);
 
-	if (vifs->bss_active && vifs->ap_active)
+	if (bss_mvmvif && ap_mvmvif && vifs->bss_active && vifs->ap_active)
 		ap_same_channel =
 			iwl_mvm_have_links_same_channel(bss_mvmvif, ap_mvmvif);
 
 	/* clients are not stand alone: enable PM if DCM */
 	if (!(client_same_channel || ap_same_channel)) {
-		if (vifs->bss_active)
+		if (bss_mvmvif && vifs->bss_active)
 			bss_mvmvif->pm_enabled = true;
-		if (vifs->p2p_active)
+		if (p2p_mvmvif && vifs->p2p_active)
 			p2p_mvmvif->pm_enabled = true;
 		return;
 	}