Changed mbedtls_platform_memcmp to memcmp for places that don't have critical data and are under baremetal

Changed back because we don't wan't to slow down the performance more than we must.
diff --git a/library/x509.c b/library/x509.c
index 1e61db8..a796760 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -588,8 +588,9 @@
         if( ret != 0 )
             goto exit;
 
+        // use regular memcmp as oid is not that critical
         if( oid[0].len != oid[1].len ||
-            mbedtls_platform_memcmp( oid[0].p, oid[1].p, oid[1].len ) != 0 )
+            memcmp( oid[0].p, oid[1].p, oid[1].len ) != 0 )
         {
             return( 1 );
         }