mb/system76/*: Disable IME by CMOS option

Add CMOS option to set IME mode. Default to "Disable" for CNL and TGL-H,
and "Enable" for TGL-U. Not set for KBL, which uses ME_CLEANER.

The HECI device must be enabled in devicetree for switching modes to
function correctly.

Change-Id: I3163dcb0a4af020c2cf6f94f2bb26380f17c253e
Signed-off-by: Tim Crawford <tcrawford@system76.com>

src/mainboard/system76/galp5/cmos.default

@@ -1,2 +1,3 @@
 boot_option=Fallback
 debug_level=Debug
+me_state=Enable