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>