ata: pata_hpt3x2n: disable fast interrupts in prereset() method

The PIO/DMA mode setting function is hardly a good place for disabling
the fast interrupts on a channel -- let's move that code to the driver's
prereset() method instead.

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>