RDS: Implement masked atomic operations

Add two CMSGs for masked versions of cswp and fadd. args
struct modified to use a union for different atomic op type's
arguments. Change IB to do masked atomic ops. Atomic op type
in rds_message similarly unionized.

Signed-off-by: Andy Grover <andy.grover@oracle.com>

net/rds/rds.h

@@ -316,8 +316,18 @@ struct rds_message {
 	struct {
 		struct rm_atomic_op {
 			int			op_type;
-			uint64_t		op_swap_add;
-			uint64_t		op_compare;
+			union {
+				struct {
+					uint64_t	compare;
+					uint64_t	swap;
+					uint64_t	compare_mask;
+					uint64_t	swap_mask;
+				} op_m_cswp;
+				struct {
+					uint64_t	add;
+					uint64_t	nocarry_mask;
+				} op_m_fadd;
+			};
 
 			u32			op_rkey;
 			u64			op_remote_addr;