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

 drivers/ata/ahci_xgene.c:564: warning: Function parameter or member 'host' not described in 'xgene_ahci_handle_broken_edge_irq'
 drivers/ata/ahci_xgene.c:564: warning: Excess function parameter 'ata_host' description in 'xgene_ahci_handle_broken_edge_irq'

Cc: Jens Axboe <axboe@kernel.dk>
Cc: Loc Ho <lho@apm.com>
Cc: Tuan Phan <tphan@apm.com>
Cc: Suman Tripathi <stripathi@apm.com>
Cc: linux-ide@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>