Fix broken accessibility "help page" link in CrOS settings.

Previously, the link added a board parameter to the URL, but this was
not correct for this particular link.

Bug: 788897
Change-Id: I2e29bdbe61f27ecf1b868c3633c793152d2d587f
Reviewed-on: https://chromium-review.googlesource.com/957598Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542307}

chrome/browser/ui/webui/settings/md_settings_localized_strings_provider.cc

@@ -250,9 +250,8 @@ void AddA11yStrings(content::WebUIDataSource* html_source) {
                           arraysize(localized_strings));
 
 #if defined(OS_CHROMEOS)
-  html_source->AddString(
-      "a11yLearnMoreUrl",
-      GetHelpUrlWithBoard(chrome::kChromeAccessibilityHelpURL));
+  html_source->AddString("a11yLearnMoreUrl",
+                         chrome::kChromeAccessibilityHelpURL);
 
   html_source->AddBoolean(
       "showExperimentalA11yFeatures",