audit: remove newline accidentally added during session id helper refactor

A newline was accidentally added during session ID helper refactorization in
commit 4d3fb709

.  This needlessly uses up buffer space, messes up syslog
formatting and makes userspace processing less efficient.  Remove it.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>