psample: Fix user API breakage

commit e43accb upstream.

Cited commit added a new attribute before the existing group reference
count attribute, thereby changing its value and breaking existing
applications on new kernels.

Before:

 # psample -l
 libpsample ERROR psample_group_foreach: failed to recv message: Operation not supported

After:

 # psample -l
 Group Num       Refcount        Group Seq
 1               1               0

Fix by restoring the value of the old attribute and remove the
misleading comments from the enumerator to avoid future bugs.

Cc: stable@vger.kernel.org
Fixes: d8bed68 ("net: psample: Add tunnel support")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reported-by: Adiel Bidani <adielb@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/uapi/linux/psample.h

@@ -3,18 +3,15 @@
 #define __UAPI_PSAMPLE_H
 
 enum {
-	/* sampled packet metadata */
 	PSAMPLE_ATTR_IIFINDEX,
 	PSAMPLE_ATTR_OIFINDEX,
 	PSAMPLE_ATTR_ORIGSIZE,
 	PSAMPLE_ATTR_SAMPLE_GROUP,
 	PSAMPLE_ATTR_GROUP_SEQ,
 	PSAMPLE_ATTR_SAMPLE_RATE,
 	PSAMPLE_ATTR_DATA,
-	PSAMPLE_ATTR_TUNNEL,
-
-	/* commands attributes */
 	PSAMPLE_ATTR_GROUP_REFCOUNT,
+	PSAMPLE_ATTR_TUNNEL,
 
 	__PSAMPLE_ATTR_MAX
 };