INT 10 - VESA SuperVGA BIOS v3.0 - GET NEAREST PIXEL CLOCK

	AX = 4F0Bh
	BL = 00h get closest pixel clock
	ECX = requested clock frequency in Hz
	DX = video mode number
Return: AL = 4Fh if function supported
	AH = status
	    00h successful
		ECX = nearest clock rate
	    01h failed