net/smc: introduce virtual ISM device support feature

This introduces virtual ISM device support feature to SMCv2.1 as the
first supplemental feature.

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/smc.h

@@ -58,9 +58,12 @@ enum smc_state {		/* possible states of an SMC socket */
 	SMC_PROCESSABORT	= 27,
 };
 
-#define SMC_FEATURE_MASK	0	/* bitmask of
-					 * supported supplemental features
-					 */
+enum smc_supplemental_features {
+	SMC_SPF_VIRT_ISM_DEV	= 0,
+};
+
+#define SMC_FEATURE_MASK \
+	(BIT(SMC_SPF_VIRT_ISM_DEV))
 
 struct smc_link_group;