libata: don't set IORDY for reset

Before issuing reset, libata configures xfermode to PIO0 which makes
some drivers turn on IORDY which may cause the controller to lock up
if the port is not occupied.  IORDY isn't necessary at this point
anyway.  Make ata_pio_need_iordy() return zero if it's being called
for reset.

This fixes bko#11703.  Reported and tracked down by Daniel Gnoutcheff
and Constantine Gavrilov.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Daniel Gnoutcheff <gnoutchd@union.edu>
Cc: Constantine Gavrilov <constantine.gavrilov@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>