Compatibility: EMS 3.2+
Expects: AX    4800H
DX    EMM handle owned by caller
                                                                  
Returns: AH    EMM status (0=successful)
                                                                  
Info: EMM will restore the page mapping to what it was upon a previous
INT 67H 4700H call with the same handle.  Device drivers and TSRs
should use this before exiting to the application.

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INT 67H 4800H: Restore Mapping Context