[202012][BRCMSAI] 4.3.7.1-2 to back out a change that broke 4.3.7.1-1

[gechiang]

This is basically the same as previous PR: (#12275)
With backing out a change that was breaking the build. Copying the same info from that PR here.

Why I did it

Pick up fix for CS00012263713 (mirrored packet with extra VLAN Tag) BRCM SAI 4.3.7.1-2

The content of this PR is almost identical to that of the 4.3.7.1-1 so the Test result of 4.3.7.1-1 is copied here.
Preliminary tests look fine. BGP neighbors were all up with proper routes programmed
interfaces are all up
Manually ran the following test cases on 7050CX3 (TD3) T0 DUT and all passed:

     fib/test_fib.py
     acl/test_acl.py
     arp/test_neighbor_mac_noptf.py
     fdb/test_fdb.py
     decap/test_decap.py
     pc/test_lag_2.py
     pc/test_po_cleanup.py
     pc/test_po_update.py
     everflow/test_everflow_ipv6.py
     everflow/test_everflow_testbed.py
     route/test_default_route.py
     ipfwd/test_dip_sip.py
     copp/test_copp.py
     crm/test_crm.py

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205

Description for the changelog

BRCM SAI 4.3.7.1-2 Pick up fix for CS00012263713 (mirrored packet with extra VLAN Tag) BRCM SAI 4.3.7.1-2