Correct the peer forwarding state table (sonic-net#281)

Description
Fixes: sonic-net/sonic-linkmgrd#101

ycabled failed to toggle peer forwarding state for active-active ports.
Use ConsumerStateTable to listen to HW_FORWARDING_STATE_PEER.

Signed-off-by: Longxiang Lyu lolv@microsoft.com

Motivation and Context
As the description

How Has This Been Tested?
On a dualtor-mixed testbed, shutdown a port on upper ToR, verified the lower ToR could toggle the nic_simulator upper ToR forwarding state to standby.

Signed-off-by: Longxiang Lyu <lolv@microsoft.com>

sonic-ycabled/ycable/ycable_utilities/y_cable_helper.py

@@ -3400,8 +3400,8 @@ def task_worker(self):
             hw_mux_cable_tbl[asic_id] = swsscommon.Table(
                 state_db[asic_id], swsscommon.STATE_HW_MUX_CABLE_TABLE_NAME)
             # TODO add definition inside app DB
-            status_tbl_peer[asic_id] = swsscommon.SubscriberStateTable(
-                appl_db[asic_id], "HW_MUX_CABLE_TABLE_PEER")
+            status_tbl_peer[asic_id] = swsscommon.ConsumerStateTable(
+                appl_db[asic_id], "HW_FORWARDING_STATE_PEER")
             fwd_state_command_tbl[asic_id] = swsscommon.SubscriberStateTable(
                 appl_db[asic_id], "FORWARDING_STATE_COMMAND")
             fwd_state_response_tbl[asic_id] = swsscommon.Table(