drm/i915/userptr: Fix error handling of mutex_lock_killable()

mutex_lock_killable() returns -EINTR on failure, not the anticipate bool
return like trylock. (Oh no, not again.)

Fixes: 484d9a84 ("drm/i915/userptr: Avoid struct_mutex recursion for mmu_invalidate_range_start")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190115221118.13304-1-chris@chris-wilson.co.ukReviewed-by: Matthew Auld <matthew.auld@intel.com>

drivers/gpu/drm/i915/i915_gem_userptr.c

@@ -150,7 +150,7 @@ userptr_mn_invalidate_range_start(struct mmu_notifier *_mn,
 			switch (mutex_trylock_recursive(unlock)) {
 			default:
 			case MUTEX_TRYLOCK_FAILED:
-				if (!mutex_lock_killable_nested(unlock, I915_MM_SHRINKER)) {
+				if (mutex_lock_killable_nested(unlock, I915_MM_SHRINKER)) {
 					i915_gem_object_put(obj);
 					return -EINTR;
 				}