cxgb4: smt: Add lock for atomic_dec_and_test

cxgb4: smt: Add lock for atomic_dec_and_test

[ Upstream commit 4a8937b83892cb69524291cae6cdabad4a8be033 ]

The atomic_dec_and_test() is not safe because it is
outside of locks.
Move the locks of t4_smte_free() to its caller,
cxgb4_smt_release() to protect the atomic decrement.

Fixes: 3bdb376e6944 ("cxgb4: introduce SMT ops to prepare for SMAC rewrite support")
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>