mb/google/eve: Use keyboard backlight for proof-of-life at boot

This feature was originally present and then dropped, but turns out
that users prefer it. Set the backlight to 50% in romstage, back to
zero in ramstage; skip enabling on the S3 resume path.

TEST=build/boot google/eve, verify keyboard backlight turns on/off
as expected.

Change-Id: I33af888d614010538f69512bbd052ed2b83fcaa5
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/76803
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/mainboard/google/eve/ec.c

@@ -15,4 +15,8 @@ void mainboard_ec_init(void)
 	};
 
 	google_chromeec_events_init(&info, acpi_is_wakeup_s3());
+
+	/* Turn off keyboard backlight after turning on in romstage */
+	if (!acpi_is_wakeup_s3())
+		google_chromeec_kbbacklight(0);
 }

src/mainboard/google/eve/romstage.c

@@ -1,11 +1,14 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include <acpi/acpi.h>
 #include <boardid.h>
 #include <string.h>
+#include <ec/google/chromeec/ec.h>
 #include <fsp/soc_binding.h>
 #include <soc/romstage.h>
 #include <console/console.h>
 #include "spd/spd.h"
+#include "ec.h"
 
 void mainboard_memory_init_params(FSPM_UPD *mupd)
 {
@@ -41,4 +44,8 @@ void mainboard_memory_init_params(FSPM_UPD *mupd)
 		printk(BIOS_WARNING, "Limiting memory to 1600MHz\n");
 		mem_cfg->DdrFreqLimit = 1600;
 	}
+
+	/* Turn on keyboard backlight to indicate we are booting */
+	if (!acpi_is_wakeup_s3())
+		google_chromeec_kbbacklight(50);
 }