Very simple adaptation to directly replace the use of HWMv1 board names
with the new identifiers:
boards:
<name>/<identifier>:
append: ...
All snippets in-tree are aligned with this format where needed.
Since the `boards` key supports regex, appends can also be applied to
multiple targets grouped by board name, SoC, CPU cluster, or variant.
Later, this can be followed up with native support for these items in
the snippet schema.
Signed-off-by: Grzegorz Swiderski <grzegorz.swiderski@nordicsemi.no>