Update psa_util.h

Remove the conditional include after the code review
diff --git a/include/mbedtls/psa_util.h b/include/mbedtls/psa_util.h
index d8449aa..a49968e 100644
--- a/include/mbedtls/psa_util.h
+++ b/include/mbedtls/psa_util.h
@@ -32,10 +32,6 @@
 #include MBEDTLS_CONFIG_FILE
 #endif
 
-#if defined(MBEDTLS_PLATFORM_C)
-#include "mbedtls/platform.h"
-#endif
-
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
 
 #include "psa/crypto.h"