libc: Fix all includes in codebase

The codebase was using non-standard headers. It is needed to replace
them by the correct ones so that we can use the new libc headers.

Change-Id: I530f71d9510cb036e69fe79823c8230afe890b9d
Acked-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/include/lib/xlat_tables/xlat_mmu_helpers.h b/include/lib/xlat_tables/xlat_mmu_helpers.h
index e1d0227..ab491e3 100644
--- a/include/lib/xlat_tables/xlat_mmu_helpers.h
+++ b/include/lib/xlat_tables/xlat_mmu_helpers.h
@@ -54,7 +54,7 @@
 
 #include <stdbool.h>
 #include <stdint.h>
-#include <sys/types.h>
+#include <string.h>
 
 /*
  * Return the values that the MMU configuration registers must contain for the