Remove unused list item from single_website_preferences.xml

This entry was added to single_website_preferences.xml during
development of r554468 but is unused and unnecessary. Tapping it
triggers a crash. This patch removes it.

Bug: 838035
Change-Id: Idb2b1c553e2a716e345903188298fe8e4b1c7e08
Reviewed-on: https://chromium-review.googlesource.com/1035782Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554861}

chrome/android/java/res/xml/single_website_preferences.xml

@@ -66,8 +66,6 @@
         android:key="midi_sysex_permission_list" />
     <org.chromium.chrome.browser.preferences.ChromeBaseListPreference
         android:key="clipboard_permission_list" />
-    <org.chromium.chrome.browser.preferences.ChromeBaseListPreference
-        android:key="usb_permission_list" />
 
     <org.chromium.chrome.browser.preferences.ButtonPreference
         android:key="reset_site_button"