ide: ide_setup_dma() assumes 8 ports

According to http://marc.info/?l=linux-ide&m=114346138611631, the drivers must
always register 8 DMA ports with ide_setup_dma(), so its last argument is not
needed. While at it, kill some useless parens in that function...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>