libata: fix a couple of doc build warnings

The kerneldoc comments for a couple of functions in drivers/ata/libata-eh.c
had fallen behind the current implementation, resulting in these doc build
warnings:

  ./drivers/ata/libata-eh.c:1449: warning: No description found for parameter 'link'
  ./drivers/ata/libata-eh.c:1449: warning: Excess function parameter 'ap' description in 'ata_eh_done'
  ./drivers/ata/libata-eh.c:1590: warning: No description found for parameter 'qc'
  ./drivers/ata/libata-eh.c:1590: warning: Excess function parameter 'dev' description in 'ata_eh_request_sense'

Update the comments and make the warnings go away.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Tejun Heo <tj@kernel.org>