mb/google/octopus/variants: Disable xHCI compliance mode

Some usb devices exhibits signal loss which causes xHCI entering
compliance mode. The resolution is to disable xHCI compliance mode.

BRANCH=octopus
BUG=b:115699781
TEST=Verified usb operation successfully.

Change-Id: I41fecaa43f4b1588a0e4bbfc465d595feb54dd24
Signed-off-by: John Zhao <john.zhao@intel.com>
Reviewed-on: https://review.coreboot.org/c/30817
Reviewed-by: Justin TerAvest <teravest@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/octopus/variants/bobba/overridetree.cb

@@ -163,4 +163,7 @@ chip soc/intel/apollolake
 			end
 		end	# - I2C 7
 	end
+
+	# Disable compliance mode
+	register "DisableComplianceMode" = "1"
 end