[LinuxBIOS] ABout pref_mem allocation

[yhlu]

Eirc,

I met one system: 4 way and every node has one ck804.

because current mem and pref-mem allocation will make every node two
mem range ( not together), So PCI_DEV(0, 0x18,1) 0x80-0xbf regs that
record mmio range will be used up.

So they there is some problem to enable VGA console, because vga
console need [0xa0000, 0xc0000) to be set as mmio too.

I remember that very beginning the PCI resource treat pref-mem io as
memio, and at last when setting that just make the upper 32 base and
limit to 0....

If you agree, I will put the old code back and add one CONFIG_NO_PREF_MEM....

YH