mb/google/octopus: Use the newly added override devicetree feature

Now that sconfig is able to support variant-specific override trees,
this change updates octopus boards to use this feature. Following
devices are moved from baseboard devicetree to variant specific
devicetree:
1. Touchscreen
2. Trackpad
3. Digitizer
4. Audio codec

BUG=b:80081934
TEST=Verified that the right devices show up in static.c for each
variant.

Change-Id: I8df0cdf4dbcd7613aa4ef4042c272eca2915da9e
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/27219
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
7 files changed