drm/i915: Remove irq-related FIXME in reset code

With the two-step reset counter increments which braket the actual
reset code and the subsequent wake-up we're guaranteeing that all the
lockless waiters _will_ be woken up. And since we unconditionally bail
out of waits with -EAGAIN (or -EIO) in that case there is not risk of
lost interrupt enabling bits when the lockless wait code races against
a gpu reset.

Let's remove this FIXME as resolved then.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -881,12 +881,6 @@ int i915_reset(struct drm_device *dev)
 		return ret;
 	}
 
-	/*
-	 * FIXME: This races pretty badly against concurrent holders of
-	 * ring interrupts. This is possible since we've started to drop
-	 * dev->struct_mutex in select places when waiting for the gpu.
-	 */
-
 	/*
 	 * rps/rc6 re-init is necessary to restore state lost after the
 	 * reset and the re-install of gt irqs. Skip for ironlake per