mb/google/skywalker: Notify EC that AP is in S0

GPIO_AP_SUSPEND_L is supposed to be high in S0, and low in S3. EC uses
this pin to determine the AP power state. This pin should be set as
early as possible in bootblock.

BUG=b:396030112
BRANCH=none
TEST=reboot pass. `powerinfo` shows S0 in EC console.

Change-Id: Ib7e9eaa19d232a37b3793bcbe268ba021e456ac7
Signed-off-by: Cong Yang <yangcong5@huaqin.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/87793
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Yidi Lin <yidilin@google.com>

src/mainboard/google/skywalker/chromeos.c

@@ -13,6 +13,7 @@ void setup_chromeos_gpios(void)
 	gpio_input(GPIO_GSC_AP_INT_ODL);
 	gpio_output(GPIO_AP_EC_WARM_RST_REQ, 0);
 	gpio_output(GPIO_XHCI_INIT_DONE, 0);
+	gpio_output(GPIO_AP_SUSPEND_L, 1);
 }
 
 void fill_lb_gpios(struct lb_gpios *gpios)

src/mainboard/google/skywalker/gpio.h

@@ -10,6 +10,7 @@
 #define GPIO_EC_AP_INT_ODL	GPIO(GBE_MDIO)
 #define GPIO_AP_EC_WARM_RST_REQ	GPIO(GBE_AUX_PPS0)
 #define GPIO_GSC_AP_INT_ODL	GPIO(GBE_AUX_PPS1)
+#define GPIO_AP_SUSPEND_L	GPIO(CONN_TOP_DATA)
 
 void setup_chromeos_gpios(void);