Fix a leftover typo in the header css import.

BUG=

Review URL: https://codereview.chromium.org/1141673002

Cr-Commit-Position: refs/heads/master@{#329555}

chrome/browser/resources/settings/settings_page/settings_page_header.html

@@ -3,7 +3,7 @@
 <link rel="import" href="chrome://resources/polymer/v0_8/iron-icons/device-icons.html">
 
 <dom-module id="cr-settings-page-header">
-  <link rel="import" type="css" href="settings_page_header_style.css">
+  <link rel="import" type="css" href="settings_page_header.css">
   <template>
     <paper-material>
       <div class="breadcrumbs">