IB/core: Remove deprecated current_seq comments

current_seq was removed since the commit below.

Fixes: 36f30e48 ("IB/core: Improve ODP to use hmm_range_fault()")
Link: https://lore.kernel.org/r/20210823035246.3506-1-lizhijian@cn.fujitsu.comSigned-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/umem_odp.c

@@ -292,9 +292,6 @@ EXPORT_SYMBOL(ib_umem_odp_release);
  * @dma_index: index in the umem to add the dma to.
  * @page: the page struct to map and add.
  * @access_mask: access permissions needed for this page.
- * @current_seq: sequence number for synchronization with invalidations.
- *               the sequence number is taken from
- *               umem_odp->notifiers_seq.
  *
  * The function returns -EFAULT if the DMA mapping operation fails.
  *