Reset Debug Watchpoint

Resets the state of a previously defined debug watchpoint;
i.e. a subsequent call to Int 31H Fn 0B02H will
indicate that the debug watchpoint has not been encountered.

Call With:

   AX     = 0B03H
   BX     = watchpoint handle

Returns:

   if function successful
   Carry flag= clear

   if function unsuccessful
   Carry flag= set
   AX     = error code
           8023H   invalid handle