src: Remove unused include <string.h>

Change-Id: Ic6b66dd8fa387e67bb0ce609fb7e2553eeb66b3c
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37888
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/drivers/generic/gfx/gfx.c

@@ -19,7 +19,6 @@
 #include <device/pci.h>
 #include <device/pci_ids.h>
 #include <stdint.h>
-#include <string.h>
 
 #include "chip.h"