ESS 1869 support: Even though the Compaq PnP BIOS lists two DMA channels
(1 and 5), use only the 8-bit channel because the second one (I think)
is the ESS's 2nd channel for duplex mode. Auto-assume DMA16 == DMA8 for
ESS chipsets.
ESS1869 bugfix: don't use the 4 byte/DMA request demand mode, it seems
to cause a problem with the chip where it fetches 4 bytes but only plays
2 bytes and therefore plays everything too fast.
ESS chipsets: assume 16-bit PCM over the 8-bit channel if no 16-bit DMA
channel given.