The SRCU_READ_FLAVOR_FAST and SRCU_READ_FLAVOR_FAST_UPDOWN comments
need repair. The former fails to not that SRCU-fast can be used in NMI
handlers, and the latter says that it goes with srcu_read_lock_fast()
when it really goes with srcu_read_lock_fast_updown(). This commit
therefore fixes both comments.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>