N900: keyboard layout needs to be loaded manually

Created by: ollieparanoid

@pieniek wrote in https://github.com/postmarketOS/pmbootstrap/issues/961#issuecomment-350322107:

One more thing - when I installed postmarket some time ago the keyboard layout was loaded out of the box, now I had to load it manually after fresh install.

@dviaznikov:

I can confirm @pieniek 's issue about keyboard layout.