scsi: scsi_dh: Document alua_rtpg_queue() arguments

Since commit 3a025e1d

 ("Add optional check for bad kernel-doc
comments") building with W=1 causes warnings to appear for issues in
kernel-doc headers. This patch avoids that the following warnings are
reported when building with W=1:

drivers/scsi/device_handler/scsi_dh_alua.c:867: warning: No description found for parameter 'pg'
drivers/scsi/device_handler/scsi_dh_alua.c:867: warning: No description found for parameter 'sdev'
drivers/scsi/device_handler/scsi_dh_alua.c:867: warning: No description found for parameter 'qdata'
drivers/scsi/device_handler/scsi_dh_alua.c:867: warning: No description found for parameter 'force'

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>