of: address: Fix parser address/size cells initialization

bus->count_cells() parses cells starting from the node's parent. This is
not good enough for parser_init() which is generally parsing a bus node.

Revert to previous behavior using of_bus_n_*_cells().

Fixes: 2f96593e

 ("of_address: Add bus type match for pci ranges parser")
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>