staging: mt7621-pci: stop using of_pci_range_to_resource

staging: mt7621-pci: stop using of_pci_range_to_resource

The logic here was already overriding the erroneous IO addresses
returned from of_pci_range_to_resource, which is the bulk of the logic.

So stop using it altogether and initialize the fields explicitly, as
done in de34fd13c28d ("powerpc/pci: Fix IO space breakage after
of_pci_range_to_resource() change").

Cc: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Reviewed-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Link: https://lore.kernel.org/r/20210410173331.57949-1-ilya.lipnitskiy@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>