PCI: tegra: Remove unused struct 'tegra_pcie_soc'

'tegra_pcie_soc' has been unused since 56e15a23 ("PCI: tegra: Add
Tegra194 PCIe support").  Remove it.

Link: https://lore.kernel.org/r/20240527160118.37069-1-linux@treblig.org


Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Niklas Cassel <cassel@kernel.org>