reproduce (this is a W=1 build):
        # https://github.com/Freescale/linux-fslc/commit/1d17a88e61fdfb2e93f6a78def034b53fc021b0f
        git remote add freescale-fslc https://github.com/Freescale/linux-fslc
        git fetch --no-tags freescale-fslc 6.6-2.1.x-imx
        git checkout 1d17a88e61fdfb2e93f6a78def034b53fc021b0f
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/regulator/