cxgb4: free mac_hlist properly

[ Upstream commit 2a8d84bf513823ba398f4b2dec41b8decf4041af ]

The locally maintained list for tracking hash mac table was
not freed during driver remove.

Signed-off-by: Arjun Vynipadath <arjun@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>