Revert "Merge remote-tracking branch 'github/3.15/exfat' into 3.15/master"

This reverts commit 9446718c5b62b2d2c697c3d9df8e5a8da5cb5975, reversing
changes made to 8136109212a7684939ff2b2cb545c5e650e74e2a.
Also adapt early_efi_write
Merge branch '3.15/cko' into 3.15/master