INT 1A - PCI BIOS v2.0c+ - WRITE CONFIGURATION BYTE (32-bit)

	AX = B18Bh
	BH = bus number
	BL = device/function number (bits 7-3 device, bits 2-0 function)
	DI = register number (0000h-00FFh)
	CL = byte to write
Return: as for AX=B10Bh
Note:	the meanings of BL and BH on return were exchanged between the initial
	  drafts of the specification and final implementation
SeeAlso: AX=B10Bh,AX=B18Ch,AX=B18Dh