PCI: tegra: Allow building as a module

PCI: tegra: Allow building as a module

Change the module macro back to builtin, which does not define an exit
function. This will prevent the module from being unloaded. There are
concerns with modules not cleaning up IRQs on unload, thus unload must be
specifically disallowed. Drop the remove callback as it is unused.

Signed-off-by: Aaron Kling <webgeek1234@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20250731-pci-tegra-module-v7-3-cad4b088b8fb@gmail.com