brcm80211: remove sparse warning in fullmac debug function

The debug function did a write operation which required a different
pointer type resulting in a sparse warning.
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Alwin Beukers <alwin@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/brcm80211/brcmfmac/dhd.h

@@ -720,7 +720,7 @@ extern int brcmf_proto_cdc_query_dcmd(struct brcmf_pub *drvr, int ifidx,
 extern int brcmf_os_proto_block(struct brcmf_pub *drvr);
 extern int brcmf_os_proto_unblock(struct brcmf_pub *drvr);
 #ifdef BCMDBG
-extern int brcmf_write_to_file(struct brcmf_pub *drvr, u8 *buf, int size);
+extern int brcmf_write_to_file(struct brcmf_pub *drvr, const u8 *buf, int size);
 #endif				/* BCMDBG */
 
 extern int brcmf_ifname2idx(struct brcmf_info *drvr_priv, char *name);

drivers/net/wireless/brcm80211/brcmfmac/dhd_linux.c

@@ -1318,7 +1318,7 @@ int brcmf_netdev_wait_pend8021x(struct net_device *ndev)
 }
 
 #ifdef BCMDBG
-int brcmf_write_to_file(struct brcmf_pub *drvr, u8 *buf, int size)
+int brcmf_write_to_file(struct brcmf_pub *drvr, const u8 *buf, int size)
 {
 	int ret = 0;
 	struct file *fp;
@@ -1338,7 +1338,7 @@ int brcmf_write_to_file(struct brcmf_pub *drvr, u8 *buf, int size)
 	}
 
 	/* Write buf to file */
-	fp->f_op->write(fp, buf, size, &pos);
+	fp->f_op->write(fp, (char __user *)buf, size, &pos);
 
 exit:
 	/* free buf before return */