drm/i915: static inline for dummy crc functions

Also use #ifdef to keep consistent with all other such cases.

Cc: Damien Lespiau <damien.lespiau@intel.com>
Acked-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 9aeddc0..b39a548 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2235,10 +2235,10 @@
 /* i915_debugfs.c */
 int i915_debugfs_init(struct drm_minor *minor);
 void i915_debugfs_cleanup(struct drm_minor *minor);
-#if defined(CONFIG_DEBUG_FS)
+#ifdef CONFIG_DEBUG_FS
 void intel_display_crc_init(struct drm_device *dev);
 #else
-void intel_display_crc_init(struct drm_device *dev) {}
+static inline void intel_display_crc_init(struct drm_device *dev) {}
 #endif
 
 /* i915_gpu_error.c */