drm/i915: Fix kerneldoc for i915_gem_shrink_all

I've botched this in

commit eb0b44adc08c0be01a027eb009e9cdadc31e65a2
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Mar 18 14:47:59 2015 +0100

    drm/i915: kerneldoc for i915_gem_shrinker.c

so let's fix it.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index f6ecbda..6743417 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -143,7 +143,7 @@
 }
 
 /**
- * i915_gem_shrink - Shrink buffer object caches completely
+ * i915_gem_shrink_all - Shrink buffer object caches completely
  * @dev_priv: i915 device
  *
  * This is a simple wraper around i915_gem_shrink() to aggressively shrink all