genl_magic: Resolve logical-op warnings

Resolve "logical 'and' applied to non-boolean constant" warnings"
that appear in W=2 builds by adding !! to a bit test.
Signed-off-by: NMark Rustad <mark.d.rustad@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/genl_magic_func.h

@@ -178,12 +178,12 @@ static int s_name ## _from_attrs_for_change(struct s_name *s,		\
 #define __assign(attr_nr, attr_flag, name, nla_type, type, assignment...)	\
 		nla = ntb[attr_nr];						\
 		if (nla) {						\
-			if (exclude_invariants && ((attr_flag) & DRBD_F_INVARIANT)) {		\
+			if (exclude_invariants && !!((attr_flag) & DRBD_F_INVARIANT)) {		\
 				pr_info("<< must not change invariant attr: %s\n", #name);	\
 				return -EEXIST;				\
 			}						\
 			assignment;					\
-		} else if (exclude_invariants && ((attr_flag) & DRBD_F_INVARIANT)) {		\
+		} else if (exclude_invariants && !!((attr_flag) & DRBD_F_INVARIANT)) {		\
 			/* attribute missing from payload, */		\
 			/* which was expected */			\
 		} else if ((attr_flag) & DRBD_F_REQUIRED) {		\