iwlwifi: mei: avoid -Wpointer-arith and -Wcast-qual warnings

These cause extra warnings (at least with W=3), avoid them.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20220130115024.59d00c6e5f09.I331bf18af0b80b5cc41b379ff0cc1b26a89dd915@changeidSigned-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/mei/main.c

@@ -312,7 +312,7 @@ static ssize_t iwl_mei_write_cyclic_buf(struct mei_cl_device *cldev,
 		memcpy(q_head + wr, hdr, tx_sz);
 	} else {
 		memcpy(q_head + wr, hdr, q_sz - wr);
-		memcpy(q_head, (u8 *)hdr + q_sz - wr, tx_sz - (q_sz - wr));
+		memcpy(q_head, (const u8 *)hdr + q_sz - wr, tx_sz - (q_sz - wr));
 	}
 
 	WRITE_ONCE(notif_q->wr_ptr, cpu_to_le32((wr + tx_sz) % q_sz));
@@ -432,7 +432,7 @@ void iwl_mei_add_data_to_ring(struct sk_buff *skb, bool cb_tx)
 	u32 q_sz;
 	u32 rd;
 	u32 wr;
-	void *q_head;
+	u8 *q_head;
 
 	if (!iwl_mei_global_cldev)
 		return;

drivers/net/wireless/intel/iwlwifi/mei/net.c

@@ -102,8 +102,8 @@ static bool iwl_mei_rx_filter_arp(struct sk_buff *skb,
 	 * src IP address    - 4 bytes
 	 * target MAC addess - 6 bytes
 	 */
-	target_ip = (void *)((u8 *)(arp + 1) +
-			     ETH_ALEN + sizeof(__be32) + ETH_ALEN);
+	target_ip = (const void *)((const u8 *)(arp + 1) +
+				   ETH_ALEN + sizeof(__be32) + ETH_ALEN);
 
 	/*
 	 * ARP request is forwarded to ME only if IP address match in the