dm cache policy: remove return from void policy_remove_mapping

No need to return from a void function.
Signed-off-by: NJoe Thornber <ejt@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

drivers/md/dm-cache-policy-internal.h

@@ -61,7 +61,7 @@ static inline int policy_writeback_work(struct dm_cache_policy *p,
 
 static inline void policy_remove_mapping(struct dm_cache_policy *p, dm_oblock_t oblock)
 {
-	return p->remove_mapping(p, oblock);
+	p->remove_mapping(p, oblock);
 }
 
 static inline void policy_force_mapping(struct dm_cache_policy *p,