Staging: ipack/bridges/tpci200: tpci200_slot_map_space() should return 0 if succeed.

tpci200_slot_map_space() should return 0 if the operation was properly
done. If not, the caller will think that something wrong happened.

This patch establish the returned value to 0. It is overwritten in case of
error.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>