Move NSSL to a separate layout file.

This allows devices of different form factors to provide their own
version of NSSL.

Bug: 243819288
Test: make, push, everything is still working
Change-Id: Ie8feafe120eb8c5aaa5d889d4145d4348534ddef
(cherry picked from commit 666354659c87f0ad67b19c83bd443fb473d37d2e)
2 files changed