INT 2C PU - Cloaking - UNTRAP I/O PORTIBM PC Portable (uses same BIOS as XT)
	AX = 002Fh
	DX = port number for which to cancel trapping
Return: CF clear if successful
	CF set on error (port out of range or reserved)
Note:	this function was first introduced with RM386 (RAM-MAN/386) v6.00
SeeAlso: AX=002Eh,AX=0030h