Revert "Disable use of HRNG in SCA-hardened mem-functions"

This reverts commit 1e96b46b032aa27d9388e395c3591b8c33005b4f.
diff --git a/library/platform_util.c b/library/platform_util.c
index 1a0fefa..db46fe9 100644
--- a/library/platform_util.c
+++ b/library/platform_util.c
@@ -142,10 +142,7 @@
 
 uint32_t mbedtls_platform_random_in_range( size_t num )
 {
-    /* Temporary force the dummy version - drawing directly from the HRNG
-     * seems to be causing issues, avoid doing that until we understood the
-     * issue, and perhaps we'll need to draw from a DRBG instead. */
-#if 1 || !defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
+#if !defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
     (void) num;
     return 0;
 #else