UBI: fix compilation warnings

The recent "UBI: fix NOR flash recovery" introduced compilation
warnings which were immediately spotted by our linux-next keeper.
This patch fixes them.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/io.c

@@ -481,16 +481,16 @@ static int nor_erase_prepare(struct ubi_device *ubi, int pnum)
 	uint32_t data = 0;
 
 	addr = (loff_t)pnum * ubi->peb_size;
-	err = ubi->mtd->write(ubi->mtd, addr, 4, &written, &data);
+	err = ubi->mtd->write(ubi->mtd, addr, 4, &written, (void *)&data);
 	if (err) {
-		ubi_err("error %d while writing 4 bytes to PEB %d:0, written "
+		ubi_err("error %d while writing 4 bytes to PEB %d:%d, written "
 			"%zd bytes", err, pnum, 0, written);
 		ubi_dbg_dump_stack();
 		return err;
 	}
 
 	addr += ubi->vid_hdr_aloffset;
-	err = ubi->mtd->write(ubi->mtd, addr, 4, &written, &data);
+	err = ubi->mtd->write(ubi->mtd, addr, 4, &written, (void *)&data);
 	if (err) {
 		ubi_err("error %d while writing 4 bytes to PEB %d:%d, written "
 			"%zd bytes", err, pnum, ubi->vid_hdr_aloffset, written);