tree: Remove unused <string.h>

Change-Id: I9ed1a82fcd3fc29124ddc406592bd45dc84d4628
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82666
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/lib/smbios_defaults.c

@@ -4,7 +4,6 @@
 #include <smbios.h>
 #include <stdint.h>
 #include <stdio.h>
-#include <string.h>
 
 /* this function will fill the corresponding locator */
 __weak void smbios_fill_dimm_locator(const struct dimm_info *dimm, struct smbios_type17 *t)