Fleex: Resume from suspend on critical battery

This patch makes Fleex EC wake up AP from s0ix when the state of
charge drops to 5%.

Demonstrated as follows:

1. Boot Fleex.
2. Run powerd_dbus_suspend.
3. On EC, run battfake 5.
4. System resumes.

BUG=b:163721887
BRANCH=Octopus
TEST=Verified on Fleex:

Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Change-Id: I4a998ad0aef5a7cfc6fd18995bde5571e6127e77
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45967
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: EricR Lai <ericr_lai@compal.corp-partner.google.com>

src/mainboard/google/octopus/variants/fleex/include/variant/ec.h

@@ -5,4 +5,9 @@
 
 #include <baseboard/ec.h>
 
+#undef MAINBOARD_EC_S0IX_WAKE_EVENTS
+#define MAINBOARD_EC_S0IX_WAKE_EVENTS \
+	(MAINBOARD_EC_S3_WAKE_EVENTS |\
+	 EC_HOST_EVENT_MASK(EC_HOST_EVENT_BATTERY_CRITICAL))
+
 #endif