Upgrade Layer Refs

See merge request !41

Dynamic selection of i.MX8MM U-Boot environment config in Linux userspace

See merge request !40

Support for i.MX8MP hardware (OSM-S, BL)

See merge request !13

Sparkle Recipe Fixes

See merge request !38

Remove KED i.MX production-tool (ptool) as it causes more pain than it helps

See merge request !39

They are already covered in the python3-can recipe or if not should
be added there.

This solves the following error message with Kirkstone:

Bitbake Fetcher Error: FetchError("Recipe uses a floating tag/branch 'rel_1.9.0' for repo 'git.kontron-electronics.de/sw/misc/apps/sparkle.git' without a fixed SRCREV yet doesn't call bb.fetch2.get_srcrev() (use SRCPV in PV for OE).", None)

docs: Split release notes and update content

See merge request !34

This will provide a better overview when the number of releases
increases.