UBI: fix use of "VID" vs. "EC" in header self-check

Looks like a typo, using UBI_EC_HDR_SIZE_CRC (note the "EC") to compute
the CRC for the VID header.

This shouldn't cause any functional change, as both structures are 64
bytes. Verified with:

	BUILD_BUG_ON(UBI_VID_HDR_SIZE_CRC != UBI_EC_HDR_SIZE_CRC);

Reported here:
http://lists.infradead.org/pipermail/linux-mtd/2013-September/048570.html

Reported by: Bill Pringlemeir <bpringlemeir@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

drivers/mtd/ubi/io.c

@@ -1299,7 +1299,7 @@ static int self_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum)
 	if (err && err != UBI_IO_BITFLIPS && !mtd_is_eccerr(err))
 		goto exit;
 
-	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_EC_HDR_SIZE_CRC);
+	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
 	hdr_crc = be32_to_cpu(vid_hdr->hdr_crc);
 	if (hdr_crc != crc) {
 		ubi_err(ubi, "bad VID header CRC at PEB %d, calculated %#08x, read %#08x",