rcu: Make _batches_completed() functions return unsigned long

Long ago, the various ->completed fields were of type long, but now are
unsigned long due to signed-integer-overflow concerns.  However, the
various _batches_completed() functions remained of type long, even though
their only purpose in life is to return the corresponding ->completed
field.  This patch cleans this up by changing these functions' return
types to unsigned long.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 0e53662..91f7e4c 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -94,7 +94,7 @@
 /*
  * Return the number of grace periods.
  */
-static inline long rcu_batches_completed(void)
+static inline unsigned long rcu_batches_completed(void)
 {
 	return 0;
 }
@@ -102,7 +102,7 @@
 /*
  * Return the number of bottom-half grace periods.
  */
-static inline long rcu_batches_completed_bh(void)
+static inline unsigned long rcu_batches_completed_bh(void)
 {
 	return 0;
 }