rcu: Get rid of some doc warnings in update.c

This commit escapes *ret, because otherwise the documentation system
thinks that this is an incomplete emphasis block:

	./kernel/rcu/update.c:65: WARNING: Inline emphasis start-string without end-string.
	./kernel/rcu/update.c:65: WARNING: Inline emphasis start-string without end-string.
	./kernel/rcu/update.c:70: WARNING: Inline emphasis start-string without end-string.
	./kernel/rcu/update.c:82: WARNING: Inline emphasis start-string without end-string.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/update.c

@@ -63,12 +63,12 @@ module_param(rcu_normal_after_boot, int, 0);
  * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section?
  * @ret:	Best guess answer if lockdep cannot be relied on
  *
- * Returns true if lockdep must be ignored, in which case *ret contains
+ * Returns true if lockdep must be ignored, in which case ``*ret`` contains
  * the best guess described below.  Otherwise returns false, in which
- * case *ret tells the caller nothing and the caller should instead
+ * case ``*ret`` tells the caller nothing and the caller should instead
  * consult lockdep.
  *
- * If CONFIG_DEBUG_LOCK_ALLOC is selected, set *ret to nonzero iff in an
+ * If CONFIG_DEBUG_LOCK_ALLOC is selected, set ``*ret`` to nonzero iff in an
  * RCU-sched read-side critical section.  In absence of
  * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side
  * critical section unless it can prove otherwise.  Note that disabling
@@ -82,7 +82,7 @@ module_param(rcu_normal_after_boot, int, 0);
  *
  * Note that if the CPU is in the idle loop from an RCU point of view (ie:
  * that we are in the section between rcu_idle_enter() and rcu_idle_exit())
- * then rcu_read_lock_held() sets *ret to false even if the CPU did an
+ * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an
  * rcu_read_lock().  The reason for this is that RCU ignores CPUs that are
  * in such a section, considering these as in extended quiescent state,
  * so such a CPU is effectively never in an RCU read-side critical section