drm/panfrost: Fix module unload

When unloading the call to pm_runtime_put_sync_suspend() will attempt to
turn the GPU cores off, however panfrost_device_fini() will have turned
the clocks off. This leads to the hardware locking up.

Instead don't call pm_runtime_put_sync_suspend() and instead simply mark
the device as suspended using pm_runtime_set_suspended(). And also
include this on the error path in panfrost_probe().

Fixes: aebe8c22

 ("drm/panfrost: Fix possible suspend in panfrost_remove")
Signed-off-by: Steven Price <steven.price@arm.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201030145833.29006-1-steven.price@arm.com