src: Use 'include <string.h>' when appropriate

Drop 'include <string.h>' when it is not used and
add it when it is missing.
Also extra lines removed, or added just before local includes.

Change-Id: Iccac4dbaa2dd4144fc347af36ecfc9747da3de20
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31966
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/security/vboot/bootmode.c

@@ -17,7 +17,6 @@
 #include <bootmode.h>
 #include <bootstate.h>
 #include <cbmem.h>
-#include <string.h>
 #include <vb2_api.h>
 #include <security/vboot/misc.h>
 #include <security/vboot/vbnv.h>

src/security/vboot/vboot_common.c

@@ -21,7 +21,6 @@
 #include <gbb_header.h>
 #include <reset.h>
 #include <stddef.h>
-#include <string.h>
 #include <security/vboot/gbb.h>
 #include <security/vboot/vboot_common.h>
 #include <security/vboot/vbnv.h>

src/security/vboot/vboot_crtm.c

@@ -18,6 +18,7 @@
 #include <cbfs.h>
 #include <security/vboot/vboot_crtm.h>
 #include <security/vboot/misc.h>
+#include <string.h>
 
 /*
  * This functions sets the TCPA log namespace

src/security/vboot/vboot_loader.c

@@ -18,7 +18,6 @@
 #include <console/console.h>
 #include <ec/google/chromeec/ec.h>
 #include <rmodule.h>
-#include <string.h>
 #include <security/vboot/misc.h>
 #include <security/vboot/symbols.h>
 #include <security/vboot/vboot_common.h>