INT 10 - Cirrus Logic BIOS - GET VIDEO MODE AVAILABILITY

	AH = 12h
	BL = A0h
	AL = video mode number (00h-7Fh)
Return: AH bit 0: video mode supported
	BX = offset of BIOS subroutine to fixup standard video parameters
		(call subroutine with DS:SI and ES:DI as returned by this call)
	DS:SI -> standard video parameters or FFFFh:FFFFh
	ES:DI -> supplemental video parameters or FFFFh:FFFFh
SeeAlso: AH=00h,AH=12h/BL=9Ah,AH=12h/BL=A1h