lint: always remove temporary files

In the error case, they survived.

Change-Id: I15167be12ff9ee03f1b3bb86b93f20cb5be02b10
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/6583
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
1 file changed