ata: pata_hpt366: Provide missing description for 'hpt366_filter()'s 'mask' param

Fixes the following W=1 kernel build warning(s):

 drivers/ata/pata_hpt366.c:200: warning: Function parameter or member 'mask' not described in 'hpt366_filter'

Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andre Hedrick <andre@linux-ide.org>
Cc: linux-ide@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/ata/pata_hpt366.c

@@ -192,6 +192,7 @@ static int hpt_dma_blacklisted(const struct ata_device *dev, char *modestr,
 /**
  *	hpt366_filter	-	mode selection filter
  *	@adev: ATA device
+ *	@mask: Current mask to manipulate and pass back
  *
  *	Block UDMA on devices that cause trouble with this controller.
  */