Remove empty stubs for detach/attach_mcast

Just use ibv_cmd_* directly.  Simplifies the code and fixes const
correctness warnings due to changes in libibverbs.

Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/src/mthca.c b/src/mthca.c
index e00c4ee..e33bf7f 100644
--- a/src/mthca.c
+++ b/src/mthca.c
@@ -127,8 +127,8 @@
 	.destroy_qp    = mthca_destroy_qp,
 	.create_ah     = mthca_create_ah,
 	.destroy_ah    = mthca_destroy_ah,
-	.attach_mcast  = mthca_attach_mcast,
-	.detach_mcast  = mthca_detach_mcast
+	.attach_mcast  = ibv_cmd_attach_mcast,
+	.detach_mcast  = ibv_cmd_detach_mcast
 };
 
 static struct ibv_context *mthca_alloc_context(struct ibv_device *ibdev, int cmd_fd)
diff --git a/src/mthca.h b/src/mthca.h
index 66751f3..9a2e362 100644
--- a/src/mthca.h
+++ b/src/mthca.h
@@ -372,7 +372,5 @@
 int mthca_alloc_av(struct mthca_pd *pd, struct ibv_ah_attr *attr,
 		   struct mthca_ah *ah);
 void mthca_free_av(struct mthca_ah *ah);
-int mthca_attach_mcast(struct ibv_qp *qp, union ibv_gid *gid, uint16_t lid);
-int mthca_detach_mcast(struct ibv_qp *qp, union ibv_gid *gid, uint16_t lid);
 
 #endif /* MTHCA_H */
diff --git a/src/verbs.c b/src/verbs.c
index b2ef3ec..f6570c6 100644
--- a/src/verbs.c
+++ b/src/verbs.c
@@ -746,13 +746,3 @@
 
 	return 0;
 }
-
-int mthca_attach_mcast(struct ibv_qp *qp, union ibv_gid *gid, uint16_t lid)
-{
-	return ibv_cmd_attach_mcast(qp, gid, lid);
-}
-
-int mthca_detach_mcast(struct ibv_qp *qp, union ibv_gid *gid, uint16_t lid)
-{
-	return ibv_cmd_detach_mcast(qp, gid, lid);
-}