score: add handling of NOTIFY_RESUME to do_notify_resume()

It's already called if TIF_NOTIFY_RESUME is set, so we only
need to add the actual work.  Note that checking for RESTORE_SIGMASK
was not needed - set_restore_sigmask() also sets SIGPENDING, so
we never RESTORE_SIGMASK without SIGPENDING.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>