vim-uefi provides syntax highlighting and filetype detection for filetypes commonly used in UEFI BIOS development.
Install vim-uefi as a Vim package (:help packages).
Here's an example for Windows:
mkdir %UserProfile%\vimfiles\pack\plugins\start
git clone https://github.com/aphroteus/vim-uefi.git %UserProfile%\vimfiles\pack\plugins\start\vim-uefi