functions: add nls_ascii to fat quirks
Created by: nl6720
All Arch Linux's officially supported kernels changed from CONFIG_FAT_DEFAULT_IOCHARSET="iso8859-1" to CONFIG_FAT_DEFAULT_IOCHARSET="ascii":
- https://github.com/archlinux/svntogit-packages/commit/34bfe7d720658c7f0d14c61f44fb2a5516073c12
- https://github.com/archlinux/svntogit-packages/commit/c75cb9e71b52eef4de9ed706f01ddf5a05f9f738
- https://github.com/archlinux/svntogit-packages/commit/283332609549a479357d2d58adf80d12e89e345f
- https://github.com/archlinux/svntogit-packages/commit/760c402675ad74417005b9abad5f997f677c801e
Although currently Arch kernels have CONFIG_NLS_ASCII=y, since it's a tristate option, it's better to add it just in case.
I'm not sure if add_module "nls_iso8859-1?" should be kept to support kernels built with CONFIG_FAT_DEFAULT_IOCHARSET="iso8859-1" or support for them is irrelevant and it can be removed.