app/controllers: Remove extra mobile_filter_header
app/controllers: Remove extra mobile_filter_header

Deletes extra copy of mobile_filter_header definition in
app/controllers/application_controller.rb

Missed this when reviewing #420.

RefugeRestrooms/refugerestrooms,RefugeRestrooms/refugerestrooms,RefugeRestrooms/refugerestrooms,RefugeRestrooms/refugerestrooms