UBI: trivial: fix comment of ubi_calculate_reserved function

The function name within the comment was not aligned with the actual
function name.
Signed-off-by: NShmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@linux.intel.com>

drivers/mtd/ubi/misc.c

@@ -92,7 +92,7 @@ int ubi_check_volume(struct ubi_device *ubi, int vol_id)
 }
 
 /**
- * ubi_calculate_rsvd_pool - calculate how many PEBs must be reserved for bad
+ * ubi_calculate_reserved - calculate how many PEBs must be reserved for bad
  * eraseblock handling.
  * @ubi: UBI device description object
  */