The Marvell bridge chips used on HighPoint SATA cards do not seem to support
the MWDMA modes (at least that could be seen in their so-called drivers :-),
so the driver needs to account for this -- to achieve this:

- add mdma_filter() method from the original patch by Bartlomiej Zolnierkiewicz
  with his consent;

- install the method for all chips to only return empty mask if a SATA drive
  is detected on HPT372{AN]/374 chips...
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>