yocto-check-layer: add debug output for the layers that were found

When debugging weird yocto-check-layer output it is useful to know
what the tool found when looking for layers.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 711e2d4d)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
(cherry picked from commit 6ff05fe0)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>