o rework pll setup code to follow h/w specification
o add hint.hifn.X.pllconfig to specify reference clock setup
requirements; default is pci66 which means the clock is
derived from the PCI bus clock and the card resides in a
66MHz slot
Tested on 7955 and 7956 cards; support for 7954 cards not enabled
since we have no cards to test against.
In collaboration with Poul-Henning Kamp.
Reviewed by: phk
MFC after: 1 week
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