alim15x3.c: M5229 (rev c8) support for DMA cd-writer

Configuration bits are not set properly for DMA on some chipset revisions.
It has already been corrected for M5229 (rev c7) but not for M5229 (rev
c8).  This leads to the bug described at
http://bugzilla.kernel.org/show_bug.cgi?id=5786

 (lost interrupt + ide bus
hangs).

Signed-off-by: Michael De Backer <micdb@skynet.be>
Signed-off-by: Adrian Bunk <bunk@stusta.de>