INT 31 - DOS32 v3.0+ - GET REAL MODE CALL BACK ADDRESS WITH IRET STACK FRAME

	AX = EE21h
	ESI = offset of the real mode call back function
Return: CF clear if successful
	    CX:DX = real mode address to call up to the protected mode
		  procedure
	CF set on error
SeeAlso: AX=EE20h