backports: update output template .gitignore for kconfig move

I clearly forgot this during the Kconfig move, the .gitignore
that is in the output template directory (and used with the
git-tracker) needs to be updated for the kconf directory move.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>