RSA PSS: remove redundant check; changelog

Remove a check introduced in the previous buffer overflow fix with keys of
size 8N+1 which the subsequent fix for buffer start calculations made
redundant.

Added a changelog entry for the buffer start calculation fix.
diff --git a/ChangeLog b/ChangeLog
index 51c002c..487a59a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,6 +10,8 @@
      data is all zeros.
 
 Bugfix
+   * Fix some invalid RSA-PSS signatures with keys of size 8N+1 that were
+     accepted. Generating these signatures required the private key.
    * Fix ssl_parse_record_header() to silently discard invalid DTLS records
      as recommended in RFC 6347 Section 4.1.2.7.