src/drivers/wifi/generic/smbios.c: Remove unused <string.h>

Found using following command:
diff <(git grep -l '#include <string.h>' -- src/) <(git grep -l 'STRINGIFY\|memcpy(\|memmove(\|memset(\|memcmp(\|memchr(\|strdup(\|strconcat(\|strnlen(\|strlen(\|strchr(\|strncpy(\|strcpy(\|strcmp(\|strncmp(\|strspn(\|strcspn(\|strstr(\|strtok_r(\|strtok(\|atol(\|strrchr(\|skip_atoi(\|vsnprintf(\|snprintf(' -- src/)

Change-Id: I2a6c5b67af1d2544159e92d4b8c06cc1f5504bd2
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60552
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
diff --git a/src/drivers/wifi/generic/smbios.c b/src/drivers/wifi/generic/smbios.c
index db22de9..9c83df6 100644
--- a/src/drivers/wifi/generic/smbios.c
+++ b/src/drivers/wifi/generic/smbios.c
@@ -3,7 +3,6 @@
 #include <device/device.h>
 #include <device/pci_ids.h>
 #include <smbios.h>
-#include <string.h>
 
 #include "wifi_private.h"