vulkan: fix release build

BUG=None
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_optional_gpu_tests_rel;tryserver.chromium.mac:mac_optional_gpu_tests_rel;tryserver.chromium.win:win_optional_gpu_tests_rel

Review URL: https://codereview.chromium.org/1900013004

Cr-Commit-Position: refs/heads/master@{#388536}

gpu/vulkan/vulkan_implementation.cc

@@ -131,6 +131,7 @@ struct VulkanInstance {
       return false;
     }
 
+#if DCHECK_IS_ON()
     // Register our error logging function.
     if (debug_report_enabled) {
       PFN_vkCreateDebugReportCallbackEXT vkCreateDebugReportCallbackEXT =
@@ -163,6 +164,7 @@ struct VulkanInstance {
         return false;
       }
     }
+#endif
 
     return true;
   }