md: don't update recovery_cp when curr_resync is ACTIVE

Don't update recovery_cp when curr_resync is MD_RESYNC_ACTIVE, otherwise
md may skip the resync of the first 3 sectors if the resync procedure is
interrupted before the first calling of ->sync_request() as shown below:

md_do_sync thread          control thread
  // setup resync
  mddev->recovery_cp = 0
  j = 0
  mddev->curr_resync = MD_RESYNC_ACTIVE

                             // e.g., set array as idle
                             set_bit(MD_RECOVERY_INTR, &&mddev_recovery)
  // resync loop
  // check INTR before calling sync_request
  !test_bit(MD_RECOVERY_INTR, &mddev->recovery

  // resync interrupted
  // update recovery_cp from 0 to 3
  // the resync of three 3 sectors will be skipped
  mddev->recovery_cp = 3

Fixes: eac58d08 ("md: Use enum for overloaded magic numbers used by mddev->curr_resync")
Cc: stable@vger.kernel.org # 6.0+
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Song Liu <song@kernel.org>