Makefiles: Rename top-level Makefiles from .inc to .mk

The .inc suffix is confusing to various tools as it's not specific to
Makefiles. This means that editors don't recognize the files, and don't
open them with highlighting and any other specific editor functionality.

This issue is also seen in the release notes generation script where
Makefiles get renamed before running cloc.

The rest of the Makefiles will be renamed in following commits.

Signed-off-by: Martin Roth <gaumless@gmail.com>
Change-Id: Idaf69c6871d0bc1ee5e2e53157b8631c55eb3db9
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80063
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Reviewed-by: Maximilian Brune <maximilian.brune@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

0 files changed, 0 insertions, 0 deletions