Change the interface to pccard_function_init. The interface is such

Change the interface to pccard_function_init.  The interface is such
that it looks for an acceptible one.  Once it finds it, it should set
the resources for the device.  I say "should" because I've not written
that.  Also set an ivar for the child of pccard.  Minor fix to the
attach message printed, we lose the slot number, which I'll have to
restore later.  Adjust the pccard ivar so that we can save the
function that corresponds to this driver so we can enable and disable
it more easily.  Save a pointer to the function so we know what we're
dealing with.

There should be some way for the driver to specify which cfg it wants
to activate.  For now the pccard_function_init function just picks
one, but we'll have to revisit this going forward.  I'm not doing it
now because I'd need some way to activate the card many times and I'm
not sure that is desirable or even safe with some cards.