drm/amdgpu: don't try to recreate sysfs entries on resume

Fixes an error on resume caused by:
fa022a9b65d2886486a022fd66b20c823cd76ad9

Signed-off-by: Alex Deucher <[e-mail]>
Cc: [e-mail]

drivers/gpu/drm/amd/amdgpu/amdgpu.h

···
 	u8                      fan_max_rpm;
 	/* dpm */
 	bool                    dpm_enabled;
+	bool                    sysfs_initialized;
 	struct amdgpu_dpm       dpm;
 	const struct firmware	*fw;	/* SMC firmware */
 	uint32_t                fw_version;

drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c

···
 {
 	int ret;
 
+	if (adev->pm.sysfs_initialized)
+		return 0;
+
 	if (adev->pm.funcs->get_temperature == NULL)
 		return 0;
 	adev->pm.int_hwmon_dev = hwmon_device_register_with_groups(adev->dev,
···
 		DRM_ERROR("Failed to register debugfs file for dpm!\n");
 		return ret;
 	}
+
+	adev->pm.sysfs_initialized = true;
 
 	return 0;
 }