Claude review: drm/bridge: Implement generic USB Type-C DP HPD bridge

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

This patch adds a new module that monitors the Type-C bus for altmode devices with DP SVID and automatically creates an HPD bridge for them.

**Issue 1: No error handling for bridge registration failure**
```c
if (is_typec_port_altmode(&alt->dev) && alt->svid == USB_TYPEC_DP_SID)
    drm_dp_hpd_bridge_register(alt->dev.parent->parent,
                               to_of_node(alt->dev.parent->fwnode));
```
`drm_dp_hpd_bridge_register()` returns a `struct device *` which can be an ERR_PTR. The return value is silently ignored. While there may not be much that can be done from a bus notifier, at least a `dev_warn()` would help debugging.

**Issue 2: Fragile device hierarchy assumption**
The comment documents the parent traversal (`alt->dev.parent->parent` = USB-C controller device), but this is a fragile assumption about the device hierarchy. If the hierarchy ever changes, this will silently break. Consider whether there's a more robust API to get the controller device.

**Issue 3: Module exit doesn't clean up bridges**
`drm_aux_hpd_typec_dp_bridge_module_exit()` only unregisters the notifier but doesn't clean up any bridges that were registered via `drm_dp_hpd_bridge_register()`. Those are `devm`-managed on the controller device, so they'll survive module unload. This may be intentional, but it means loading/unloading this module repeatedly could have unexpected interactions.

**Minor: Missing MODULE_AUTHOR**

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