arm/Kconfig: Keep Kconfig default entries in default.mak as documentation

arm/Kconfig: Keep Kconfig default entries in default.mak as documentation

When we moved the arm default CONFIGs into Kconfig and removed them
from default.mak, we made it harder to identify which CONFIGs are
selected by default in case users want to disable them.

Bring back the default entries into default.mak, but keep them
commented out. This way users can keep their workflows of editing
default.mak to remove build options without needing to search through
Kconfig.

Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 20230523180525.29994-3-farosas@suse.de
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>