mtd: cfi: fix writebufsize initialization

When initializing mtd->writebufsize, we must take into account
possible flash chip interleaving. Wrong writebufsize initialization
caused UBIFS recovery issues resulting in unmountable UBIFS file
system on NOR flash partitions.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Guillaume LECERF <glecerf@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/chips/cfi_cmdset_0020.c b/drivers/mtd/chips/cfi_cmdset_0020.c
index c04b765..ed56ad3 100644
--- a/drivers/mtd/chips/cfi_cmdset_0020.c
+++ b/drivers/mtd/chips/cfi_cmdset_0020.c
@@ -238,7 +238,7 @@
 	mtd->resume = cfi_staa_resume;
 	mtd->flags = MTD_CAP_NORFLASH & ~MTD_BIT_WRITEABLE;
 	mtd->writesize = 8; /* FIXME: Should be 0 for STMicro flashes w/out ECC */
-	mtd->writebufsize = 1 << cfi->cfiq->MaxBufWriteSize;
+	mtd->writebufsize = cfi_interleave(cfi) << cfi->cfiq->MaxBufWriteSize;
 	map->fldrv = &cfi_staa_chipdrv;
 	__module_get(THIS_MODULE);
 	mtd->name = map->name;