[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/nand/rtc_from4.c b/drivers/mtd/nand/rtc_from4.c
index bc9d849..64ccf4c 100644
--- a/drivers/mtd/nand/rtc_from4.c
+++ b/drivers/mtd/nand/rtc_from4.c
@@ -487,7 +487,7 @@
 		if (!(rtn & ERR_STAT_ECC_AVAILABLE)) {
 			er_stat |= 1 << 1;	/* err_ecc_not_avail */
 		} else {
-			len = mtd->oobblock;
+			len = mtd->writesize;
 			buf = kmalloc(len, GFP_KERNEL);
 			if (!buf) {
 				printk(KERN_ERR "rtc_from4_errstat: Out of memory!\n");