IPoIB: Fix build with CONFIG_INFINIBAND_IPOIB_CM=n

With the new netlink support in commit 862096a8bbf8 ("IB/ipoib: Add more
rtnl_link_ops callbacks") we need ipoib_set_mode() to be available even
if connected mode isn't built.  Move the function from ipoib_cm.c to
ipoib_main.c (and make a few CM-related macros available unconditonally).

This fixes the build error

    drivers/built-in.o: In function 'ipoib_changelink':
    ipoib_netlink.c:(.text+0x6a5fc9): undefined reference to 'ipoib_set_mode'
    ipoib_netlink.c:(.text+0x6a5fe3): undefined reference to 'ipoib_set_mode'

when CONFIG_INFINIBAND_IPOIB_CM isn't set.

Reported-by: Randy Dunlap <rdunlap@xenotime.net>
Reported-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index 196eb52..07ca6fd 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -535,14 +535,14 @@
 void ipoib_set_ethtool_ops(struct net_device *dev);
 int ipoib_set_dev_features(struct ipoib_dev_priv *priv, struct ib_device *hca);
 
-#ifdef CONFIG_INFINIBAND_IPOIB_CM
-
 #define IPOIB_FLAGS_RC		0x80
 #define IPOIB_FLAGS_UC		0x40
 
 /* We don't support UC connections at the moment */
 #define IPOIB_CM_SUPPORTED(ha)   (ha[0] & (IPOIB_FLAGS_RC))
 
+#ifdef CONFIG_INFINIBAND_IPOIB_CM
+
 extern int ipoib_max_conn_qp;
 
 static inline int ipoib_cm_admin_enabled(struct net_device *dev)