Add system_dlkm notices in DEFAULT_LICENSE_XML_PATHS

Adds /system_dlkm/etc/NOTICE.xml.gz in DEFAULT_LICENSE_XML_PATHS
so they can be part of the generated NOTICE.html

Test: Settings -> About Phone -> Legal Information -> Third-party licenses
Test: Inspect /data/user_de/0/com.android.settings/cache/NOTICE.html
Bug: 372589161
Change-Id: Idd3c5306075f96b75e7eb1c3993098bf642bec42
Signed-off-by: Ramji Jiyani <ramjiyani@google.com>