[MTD] Introduce writesize

At least two flashes exists that have the concept of a minimum write unit,
similar to NAND pages, but no other NAND characteristics.  Therefore, rename
the minimum write unit to "writesize" for all flashes, including NAND.

Signed-off-by: Joern Engel <joern@wh.fh-wedel.de>
diff --git a/drivers/mtd/onenand/onenand_bbt.c b/drivers/mtd/onenand/onenand_bbt.c
index 4510d33..aafd7c2 100644
--- a/drivers/mtd/onenand/onenand_bbt.c
+++ b/drivers/mtd/onenand/onenand_bbt.c
@@ -87,13 +87,13 @@
 
 			/* No need to read pages fully,
 			 * just read required OOB bytes */
-			ret = mtd->read_oob(mtd, from + j * mtd->oobblock + bd->offs,
+			ret = mtd->read_oob(mtd, from + j * mtd->writesize + bd->offs,
 						readlen, &retlen, &buf[0]);
 
 			if (ret)
 				return ret;
 
-			if (check_short_pattern(&buf[j * scanlen], scanlen, mtd->oobblock, bd)) {
+			if (check_short_pattern(&buf[j * scanlen], scanlen, mtd->writesize, bd)) {
 				bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
 				printk(KERN_WARNING "Bad eraseblock %d at 0x%08x\n",
 					i >> 1, (unsigned int) from);