net: airoha: Always check return value from airoha_ppe_foe_get_entry()

airoha_ppe_foe_get_entry routine can return NULL, so check the returned
pointer is not NULL in airoha_ppe_foe_flow_l2_entry_update()

Fixes: b81e0f2 ("net: airoha: Add FLOW_CLS_STATS callback support")
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20250618-check-ret-from-airoha_ppe_foe_get_entry-v2-1-068dcea3cc66@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: LorenzoBianconi

drivers/net/ethernet/airoha/airoha_ppe.c

@@ -809,8 +809,10 @@ airoha_ppe_foe_flow_l2_entry_update(struct airoha_ppe *ppe,
 		int idle;
 
 		hwe = airoha_ppe_foe_get_entry(ppe, iter->hash);
-		ib1 = READ_ONCE(hwe->ib1);
+		if (!hwe)
+			continue;
 
+		ib1 = READ_ONCE(hwe->ib1);
 		state = FIELD_GET(AIROHA_FOE_IB1_BIND_STATE, ib1);
 		if (state != AIROHA_FOE_STATE_BIND) {
 			iter->hash = 0xffff;