entropy_poll: Updated documentation for entropy_poll loop.

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/library/entropy_poll.c b/library/entropy_poll.c
index 52be9f5..5eb6d7f 100644
--- a/library/entropy_poll.c
+++ b/library/entropy_poll.c
@@ -61,8 +61,8 @@
 
     /*
      * BCryptGenRandom takes ULONG for size, which is smaller than size_t on
-     * 64-bit Windows platforms. Ensure len's value can be safely converted into
-     * a ULONG.
+     * 64-bit Windows platforms. Extract entropy in chunks of len (dependent
+     * on ULONG_MAX) size.
      */
     while (len != 0) {
         unsigned long ulong_bytes =