lib,console,sbom: Rename 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.

Signed-off-by: Martin Roth <gaumless@gmail.com>
Change-Id: I9eabe84d55fd9f434e4128866810c0e4970f2ae7
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80081
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Maximilian Brune <maximilian.brune@9elements.com>
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
diff --git a/src/console/Makefile.inc b/src/console/Makefile.mk
similarity index 100%
rename from src/console/Makefile.inc
rename to src/console/Makefile.mk
diff --git a/src/lib/Makefile.inc b/src/lib/Makefile.mk
similarity index 100%
rename from src/lib/Makefile.inc
rename to src/lib/Makefile.mk
diff --git a/src/lib/gnat/Makefile.inc b/src/lib/gnat/Makefile.mk
similarity index 100%
rename from src/lib/gnat/Makefile.inc
rename to src/lib/gnat/Makefile.mk
diff --git a/src/sbom/Makefile.inc b/src/sbom/Makefile.mk
similarity index 100%
rename from src/sbom/Makefile.inc
rename to src/sbom/Makefile.mk