mb/google/mancomb: set PSPP policy to balanced

Not sure which policy we should select here or if that should be done in
the board-specific devicetree overrides instead of the baseboard.

BUG=b:188793754

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I792d909ce75cb73571c9fec58c18f749ea3ae029
Reviewed-on: https://review.coreboot.org/c/coreboot/+/54933
Reviewed-by: Matt Papageorge <matthewpapa07@gmail.com>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/mancomb/variants/baseboard/devicetree.cb

@@ -50,6 +50,8 @@ chip soc/amd/cezanne
 	# Enable S0i3 support
 	register "s0ix_enable" = "1"
 
+	register "pspp_policy" = "DXIO_PSPP_BALANCED"
+
 	device domain 0 on
 		device ref gpp_bridge_0 on end # WLAN
 		device ref gpp_bridge_1 on end # SD