crypt32: In CRYPT_CollectionAdvanceEnum remove unneeded statement (cppcheck).

Signed-off-by: Fabian Maurer <dark.shadow4@web.de>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
diff --git a/dlls/crypt32/collectionstore.c b/dlls/crypt32/collectionstore.c
index 8b90270..2c2398d 100644
--- a/dlls/crypt32/collectionstore.c
+++ b/dlls/crypt32/collectionstore.c
@@ -164,7 +164,6 @@
         Context_AddRef(child);
         child = contextFuncs->enumContext(storeEntry->store, child);
         Context_Release(prev);
-        prev = NULL;
     }
     else
     {