When calling the deprecated `bp_core_get_notifications_for_user()` function, the `bp_core_get_notifications_for_user` filter is called two times: once in `bp_notifications_get_notifications_for_user()` and again `bp_core_get_notifications_for_user()`.

Here we remove the deprecated one and rely on the one in `bp_notifications_get_notifications_for_user()` to do its job.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8628 cdf35c40-ae34-48e0-9cc9-0c9da1808c22