UBI: fix s/then/than/ typos

Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index 0a8c7ea..f702a16 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -27,7 +27,7 @@
 	  The default value should be OK for SLC NAND flashes, NOR flashes and
 	  other flashes which have eraseblock life-cycle 100000 or more.
 	  However, in case of MLC NAND flashes which typically have eraseblock
-	  life-cycle less then 10000, the threshold should be lessened (e.g.,
+	  life-cycle less than 10000, the threshold should be lessened (e.g.,
 	  to 128 or 256, although it does not have to be power of 2).
 
 config MTD_UBI_BEB_RESERVE