Datasheet says vge(4) controllers support DAC but it seems that's

Datasheet says vge(4) controllers support DAC but it seems that's
not true on old PCI based controllers.  DAC configuration is read
from EEPROM in device reset phase and driver can override DAC
configuration.  However I guess there is an undocumented reason why
EEPROM configuration does not enable DAC so do not blindly override
DAC configuration.  Recent PCIe based controllers are supposed to
support 64bit DMA so allow 64bit DMA only on PCIe based controllers.

PR:		kern/157184
MFC after:	1 week