mei: constify buffer in the write functions calls

The write buffer should not by modified so make it constant. Also
hitchhike some style fixes on the way in the interface and rename
mei_me_write_message to mei_me_hbuf_write for consistency.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/hw-txe.c

@@ -691,7 +691,8 @@ static void mei_txe_hw_config(struct mei_device *dev)
  */
 
 static int mei_txe_write(struct mei_device *dev,
-		struct mei_msg_hdr *header, unsigned char *buf)
+			 struct mei_msg_hdr *header,
+			 const unsigned char *buf)
 {
 	struct mei_txe_hw *hw = to_txe_hw(dev);
 	unsigned long rem;