zram: allow request end to coincide with disksize

Pass valid_io_request() checks if request end coincides with disksize
(end equals bound), only fail if we attempt to read beyond the bound.

mkfs.ext2 produces numerous errors:
[ 2164.632747] quiet_error: 1 callbacks suppressed
[ 2164.633260] Buffer I/O error on device zram0, logical block 153599
[ 2164.633265] lost page write due to I/O error on zram0
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/zram/zram_drv.c

@@ -180,7 +180,7 @@ static inline int valid_io_request(struct zram *zram, struct bio *bio)
 	end = start + (bio->bi_size >> SECTOR_SHIFT);
 	bound = zram->disksize >> SECTOR_SHIFT;
 	/* out of range range */
-	if (unlikely(start >= bound || end >= bound || start > end))
+	if (unlikely(start >= bound || end > bound || start > end))
 		return 0;
 
 	/* I/O request is valid */