i915: remove pm_qos request on error

commit 22accca0 upstream.

Not removing pm qos request and free memory for it can cause crash,
when some other driver use pm qos. For example, this oops:

BUG: unable to handle kernel paging request at fffffffffffffff8
IP: [<ffffffff81307a6b>] plist_add+0x5b/0xd0
Call Trace:
 [<ffffffff810acf25>] pm_qos_update_target+0x125/0x1e0
 [<ffffffff810ad071>] pm_qos_add_request+0x91/0x100
 [<ffffffffa053ec14>] e1000_open+0xe4/0x5b0 [e1000e]

was caused by earlier i915 probe failure:

[drm:i915_report_and_clear_eir] *ERROR* EIR stuck: 0x00000010, masking
[drm:init_ring_common] *ERROR* render ring initialization failed ctl 0001f001 head 00003004 tail 00000000 start 00003000
[drm:i915_driver_load] *ERROR* failed to init modeset
i915: probe of 0000:00:02.0 failed with error -5

Bug report:
http://bugzilla.redhat.com/show_bug.cgi?id=1057533Reported-by: Giandomenico De Tullio <ghisha@gmail.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
[danvet: Drop unnecessary code movement.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/i915/i915_dma.c

@@ -1687,6 +1687,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 
 	intel_teardown_gmbus(dev);
 	intel_teardown_mchbar(dev);
+	pm_qos_remove_request(&dev_priv->pm_qos);
 	destroy_workqueue(dev_priv->wq);
 out_mtrrfree:
 	if (dev_priv->mm.gtt_mtrr >= 0) {