hpt366: disallow Ultra133 for HPT374

Eliminate UltraATA/133 support for HPT374 -- the chip isn't capable of this mode
according to the manual, and doesn't even seem to tolerate 66 MHz DPLL clock...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Geller Sandor <wildy@petra.hos.u-szeged.hu>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>