Revert "flow_offload: action should not be NULL when it is referenced"

This reverts commit 9ea3e52c5b.

Cited commit added a check to make sure 'action' is not NULL, but
'action' is already dereferenced before the check, when calling
flow_offload_has_one_action().

Therefore, the check does not make any sense and results in a smatch
warning:

include/net/flow_offload.h:322 flow_action_mixed_hw_stats_check() warn:
variable dereferenced before check 'action' (see line 319)

Fix by reverting this commit.

Cc: gushengxian <gushengxian@yulong.com>
Fixes: 9ea3e52c5b ("flow_offload: action should not be NULL when it is referenced")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20210819105842.1315705-1-idosch@idosch.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/flow_offload.h

@@ -319,14 +319,12 @@ flow_action_mixed_hw_stats_check(const struct flow_action *action,
 	if (flow_offload_has_one_action(action))
 		return true;
 
-	if (action) {
-		flow_action_for_each(i, action_entry, action) {
-			if (i && action_entry->hw_stats != last_hw_stats) {
-				NL_SET_ERR_MSG_MOD(extack, "Mixing HW stats types for actions is not supported");
-				return false;
-			}
-			last_hw_stats = action_entry->hw_stats;
+	flow_action_for_each(i, action_entry, action) {
+		if (i && action_entry->hw_stats != last_hw_stats) {
+			NL_SET_ERR_MSG_MOD(extack, "Mixing HW stats types for actions is not supported");
+			return false;
 		}
+		last_hw_stats = action_entry->hw_stats;
 	}
 	return true;
 }