drm/i915: Avoid early timeout during AUX transfers

Since wait_for_atomic doesn't re-check the wait-for condition after
expiry of the timeout it can fail when called from non-atomic context
even if the condition is set correctly before the expiry. Fix this by
using the non-atomic wait_for instead.

Due to the relatively long 10ms timeout, probably this didn't cause any
real problems, but fix it in any case for consistency.

Fixes: 0351b939 ("drm/i915: Do not lie about atomic timeout granularity")
CC: Chris Wilson <chris@chris-wilson.co.uk>
CC: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
CC: drm-intel-fixes@lists.freedesktop.org
Link: http://patchwork.freedesktop.org/patch/msgid/1467110253-16046-5-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/intel_dp.c

@@ -727,7 +727,7 @@ intel_dp_aux_wait_done(struct intel_dp *intel_dp, bool has_aux_irq)
 		done = wait_event_timeout(dev_priv->gmbus_wait_queue, C,
 					  msecs_to_jiffies_timeout(10));
 	else
-		done = wait_for_atomic(C, 10) == 0;
+		done = wait_for(C, 10) == 0;
 	if (!done)
 		DRM_ERROR("dp aux hw did not signal timeout (has irq: %i)!\n",
 			  has_aux_irq);