mb/google/guybrush,skyrim: add missing string.h include

string.h defines the memset function.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I286557d6ad83990bc101eaa930bde04345859c0b
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68845
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Fred Reitberger <reitbergerfred@gmail.com>

src/mainboard/google/guybrush/mainboard.c

@@ -12,6 +12,7 @@
 #include <gpio.h>
 #include <soc/acpi.h>
 #include <variant/ec.h>
+#include <string.h>
 
 #define BACKLIGHT_GPIO			GPIO_129
 #define WWAN_AUX_RST_GPIO		GPIO_18

src/mainboard/google/skyrim/mainboard.c

@@ -6,6 +6,7 @@
 #include <console/console.h>
 #include <device/device.h>
 #include <soc/acpi.h>
+#include <string.h>
 #include <variant/ec.h>
 
 /*