nvim: lua: plugins: Do not use file type loading for Haskell plugins

The syntax plugin does not seem to take an effect, when the file type
loading feature from packer is used. So, remove it.

nvim/.config/nvim/lua/plugins.lua

@@ -124,14 +124,10 @@ local init = function ()
   }
   -- Language support & syntax highlighting
   -- Haskell
-  use {
-    'neovimhaskell/haskell-vim',
-    ft = 'haskell'
-  }
+  use 'neovimhaskell/haskell-vim'
   use {
     'ndmitchell/ghcid',
-    rtp = 'plugins/nvim',
-    ft = 'haskell'
+    rtp = 'plugins/nvim'
   }
   -- For C, Lua and Rust
   use {