Cut out another chunk from leftover.c and put linecard related code
into a separate file.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20230828061657.300667-13-jiri@resnulli.usSigned-off-by: Jakub Kicinski <kuba@kernel.org>