This is used by kbuild to load preset Kconfig options.  We need to
ignore it, otherwise git clean kills it.

Signed-off-by: Borislav Petkov <[email protected]>
Cc: Michal Marek <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>