drm/tilcdc: Fix removal actions in case of failed probe

drm/tilcdc: Fix removal actions in case of failed probe

commit a585c7ef9cabda58088916baedc6573e9a5cd2a7 upstream.

The drm_kms_helper_poll_fini() and drm_atomic_helper_shutdown() helpers
should only be called when the device has been successfully registered.
Currently, these functions are called unconditionally in tilcdc_fini(),
which causes warnings during probe deferral scenarios.

[    7.972317] WARNING: CPU: 0 PID: 23 at drivers/gpu/drm/drm_atomic_state_helper.c:175 drm_atomic_helper_crtc_duplicate_state+0x60/0x68
...
[    8.005820]  drm_atomic_helper_crtc_duplicate_state from drm_atomic_get_crtc_state+0x68/0x108
[    8.005858]  drm_atomic_get_crtc_state from drm_atomic_helper_disable_all+0x90/0x1c8
[    8.005885]  drm_atomic_helper_disable_all from drm_atomic_helper_shutdown+0x90/0x144
[    8.005911]  drm_atomic_helper_shutdown from tilcdc_fini+0x68/0xf8 [tilcdc]
[    8.005957]  tilcdc_fini [tilcdc] from tilcdc_pdev_probe+0xb0/0x6d4 [tilcdc]

Fix this by rewriting the failed probe cleanup path using the standard
goto error handling pattern, which ensures that cleanup functions are
only called on successfully initialized resources. Additionally, remove
the now-unnecessary is_registered flag.

Cc: stable@vger.kernel.org
Fixes: 3c4babae3c4a ("drm: Call drm_atomic_helper_shutdown() at shutdown/remove time for misc drivers")
Signed-off-by: Kory Maincent (TI.com) <kory.maincent@bootlin.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patch.msgid.link/20251125090546.137193-1-kory.maincent@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>