Revert "drm/i915: fix context/engine cleanup order"

Revert "drm/i915: fix context/engine cleanup order"

This reverts commit 1b39a917a9e00378c02c50ad86632ed3d872bfad.

Chris retracted his reviewed-by (which I failed to notice) and somehow
it blows up (I did it again!) as reported by Mika with the below
backtrace on module reload:

[   58.170374] IP: [<ffffffffa00e04d3>]
intel_logical_ring_cleanup+0x83/0x100 [i915]
...
[   58.170469] Call Trace:
[   58.170479]  [<ffffffffa00d0ed4>] i915_gem_cleanup_engines+0x34/0x60
[i915]
[   58.170493]  [<ffffffffa0154520>] i915_driver_unload+0x140/0x220
[i915]
[   58.170497]  [<ffffffff8154a4f4>] drm_dev_unregister+0x24/0xa0
[   58.170501]  [<ffffffff8154aace>] drm_put_dev+0x1e/0x60
[   58.170506]  [<ffffffffa00912a0>] i915_pci_remove+0x10/0x20 [i915]
[   58.170510]  [<ffffffff814766e4>] pci_device_remove+0x34/0xb0
[   58.170514]  [<ffffffff8156e7d5>] __device_release_driver+0x95/0x140
[   58.170518]  [<ffffffff8156e97c>] driver_detach+0xbc/0xc0
[   58.170521]  [<ffffffff8156d883>] bus_remove_driver+0x53/0xd0
[   58.170525]  [<ffffffff8156f3a7>] driver_unregister+0x27/0x50
[   58.170528]  [<ffffffff81475725>] pci_unregister_driver+0x25/0x70
[   58.170531]  [<ffffffff8154c274>] drm_pci_exit+0x74/0x90
[   58.170543]  [<ffffffffa0154cb0>] i915_exit+0x20/0x1aa [i915]
[   58.170548]  [<ffffffff8111846f>] SyS_delete_module+0x18f/0x1f0

Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Nick Hoath <nicholas.hoath@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>