firewire: ohci: skip regAccessFail checks on Agere and VIA controllers

The datasheets of
  - Agere FW323 rev 5
  - VIA VT6306, VT6307, VT6308, VT6315, VT6320, VT6325, VT6330
specify that intEvent.bit18 (regAccessFail according to OHCI 1.1) is
always 0.

I do not have datasheets of the other Agere 1394 link layer controllers
but the product briefs of FW322, FW323, FW643, and FW643E state that
they can be configured via PCI bus commands or EEPROM to operate in
either OHCI 1.0 or OHCI 1.1 mode.  This implies that their PHY and their
PHY--link interface cannot exhibit the kind of unreliability which
brought the regAccessFail misfeature into OHCI 1.1.

So we can skip the regAccessFail test on these chips.  Now my
test_cycle_time tool gets from 19 million samples per minute to
36 million samples per minute with FW643E on an Unibrain "Fireboard800-e
Pro Dual" card.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
1 file changed