drm/bridge: synopsys: dw-dp: fix error paths of dw_dp_bind

In the Linux kernel, the following vulnerability has been resolved:

drm/bridge: synopsys: dw-dp: fix error paths of dw_dp_bind

Fix several issues in dw_dp_bind() error handling:

1. Missing return after drm_bridge_attach() failure - the function
continued execution instead of returning an error.

2. Resource leak: drm_dp_aux_register() is not a devm function, so
drm_dp_aux_unregister() must be called on all error paths after
aux registration succeeds. This affects errors from:
- drm_bridge_attach()
- phy_init()
- devm_add_action_or_reset()
- platform_get_irq()
- devm_request_threaded_irq()

3. Bug fix: platform_get_irq() returns the IRQ number or a negative
error code, but the error path was returning ERR_PTR(ret) instead
of ERR_PTR(dp->irq).

Use a goto label for cleanup to ensure consistent error handling.