Adds the required KCSAN instrumentation for barriers if CONFIG_SMP.
KCSAN supports modeling the effects of:
smp_mb()
smp_rmb()
smp_wmb()
smp_store_release()
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>