drm/amdgpu/display: Fix reload driver error

Issue:
Will have follow error when reload driver:
[ 3986.567739] sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:07.0/drm_dp_aux_dev'
[ 3986.567743] CPU: 6 PID: 1767 Comm: modprobe Tainted: G           OE     5.0.0-rc1-custom #1
[ 3986.567745] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 3986.567746] Call Trace:
......
[ 3986.567808]  drm_dp_aux_register_devnode+0xdc/0x140 [drm_kms_helper]
......
[ 3986.569081] kobject_add_internal failed for drm_dp_aux_dev with -EEXIST, don't try to register things with the same name in the same directory.

Reproduce sequences:
1.modprobe amdgpu
2.modprobe -r amdgpu
3.modprobe amdgpu

Root cause:
When unload driver, it doesn't unregister aux.

v2: Don't use has_aux
Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -3675,6 +3675,13 @@ int amdgpu_dm_connector_atomic_get_property(struct drm_connector *connector,
 	return ret;
 }
 
+static void amdgpu_dm_connector_unregister(struct drm_connector *connector)
+{
+	struct amdgpu_dm_connector *amdgpu_dm_connector = to_amdgpu_dm_connector(connector);
+
+	drm_dp_aux_unregister(&amdgpu_dm_connector->dm_dp_aux.aux);
+}
+
 static void amdgpu_dm_connector_destroy(struct drm_connector *connector)
 {
 	struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector);
@@ -3703,6 +3710,11 @@ static void amdgpu_dm_connector_destroy(struct drm_connector *connector)
 	drm_dp_cec_unregister_connector(&aconnector->dm_dp_aux.aux);
 	drm_connector_unregister(connector);
 	drm_connector_cleanup(connector);
+	if (aconnector->i2c) {
+		i2c_del_adapter(&aconnector->i2c->base);
+		kfree(aconnector->i2c);
+	}
+
 	kfree(connector);
 }
 
@@ -3760,7 +3772,8 @@ static const struct drm_connector_funcs amdgpu_dm_connector_funcs = {
 	.atomic_duplicate_state = amdgpu_dm_connector_atomic_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 	.atomic_set_property = amdgpu_dm_connector_atomic_set_property,
-	.atomic_get_property = amdgpu_dm_connector_atomic_get_property
+	.atomic_get_property = amdgpu_dm_connector_atomic_get_property,
+	.early_unregister = amdgpu_dm_connector_unregister
 };
 
 static int get_modes(struct drm_connector *connector)