purism/librem13v2: Clean up devicetree

- remove unused I2C, serialIO defs
- set PL2 override, VR mailbox cmd based on SKL-U ref board,
  as values copied from google/chell are for SKL-Y

Change-Id: I3a138c28d0322df6cb41ec1a845ae31602cb69a7
Signed-off-by: Youness Alaoui <youness.alaoui@puri.sm>
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/19941
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>
1 file changed