drm/radeon: Suspend and resume clients with client helpers

Replace calls to radeon_fbdev_set_suspend() with calls to the client
functions drm_client_dev_suspend() and drm_client_dev_resume(). Any
registered in-kernel client will now receive suspend and resume events.

v4:
- refer to radeon_fbdev_set_suspend() in commit description (Jonathan)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: Xinhui Pan <Xinhui.Pan@amd.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241014085740.582287-11-tzimmermann@suse.de