This function disconnects from a card in a reader, and frees the card
structure. Any locks made by the application must be released before
calling this function.
The action parameter is not used at the moment and should be set to 0.
The card is not reset nor powered down after the operation.
RETURN VALUE
If an error occurred, a negative error code is returned, as described
in sc_error(3). Otherwise, the function will return 0.