nfc: constify payload argument in nci_send_cmd()

The nci_send_cmd() payload argument is passed directly to skb_put_data()
which already accepts a pointer to const, so make it const as well for
correctness and safety.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/nfc/nci_core.h

@@ -360,7 +360,7 @@ int nci_core_rsp_packet(struct nci_dev *ndev, __u16 opcode,
 int nci_core_ntf_packet(struct nci_dev *ndev, __u16 opcode,
 			struct sk_buff *skb);
 void nci_rx_data_packet(struct nci_dev *ndev, struct sk_buff *skb);
-int nci_send_cmd(struct nci_dev *ndev, __u16 opcode, __u8 plen, void *payload);
+int nci_send_cmd(struct nci_dev *ndev, __u16 opcode, __u8 plen, const void *payload);
 int nci_send_data(struct nci_dev *ndev, __u8 conn_id, struct sk_buff *skb);
 int nci_conn_max_data_pkt_payload_size(struct nci_dev *ndev, __u8 conn_id);
 void nci_data_exchange_complete(struct nci_dev *ndev, struct sk_buff *skb,

net/nfc/nci/core.c

@@ -1332,7 +1332,7 @@ int nci_send_frame(struct nci_dev *ndev, struct sk_buff *skb)
 EXPORT_SYMBOL(nci_send_frame);
 
 /* Send NCI command */
-int nci_send_cmd(struct nci_dev *ndev, __u16 opcode, __u8 plen, void *payload)
+int nci_send_cmd(struct nci_dev *ndev, __u16 opcode, __u8 plen, const void *payload)
 {
 	struct nci_ctrl_hdr *hdr;
 	struct sk_buff *skb;