nfc: mei_phy: constify buffer passed to mei_nfc_send()

The buffer passed to mei_nfc_send() can be const for correctness and
safety.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/nfc/mei_phy.c

@@ -202,7 +202,7 @@ static int mei_nfc_connect(struct nfc_mei_phy *phy)
 	return r;
 }
 
-static int mei_nfc_send(struct nfc_mei_phy *phy, u8 *buf, size_t length)
+static int mei_nfc_send(struct nfc_mei_phy *phy, const u8 *buf, size_t length)
 {
 	struct mei_nfc_hdr *hdr;
 	u8 *mei_buf;