PCI: tegra: Remove PCI_REASSIGN_ALL_BUS use on Tegra

Bridge primary, secondary, and subordinate bus numbers power up as zero,
and Tegra firmware doesn't program them.

pci_scan_bridge_extend() automatically programs these bus numbers if they
are zero, so we don't need to set the PCI_REASSIGN_ALL_BUS flag for Tegra.

Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
[bhelgaas: changelog]
Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>
Acked-by: Thierry Reding <treding@nvidia.com>