hpt366: fix HPT370 DMA timeouts

The big driver change in 2.4.19-rc1 introduced a regression for many HPT370[A]
chips -- DMA stopped to work completely, only causing endless timeouts...

The culprit has been identified (at last!): it turned to be the code resetting
the DMA state machine before each transfer. Stop doing it now as this counter-
measure has clearly caused more harm than good.

This should fix the kernel.org bug #7703.

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