vppinfra: refactor use of CLIB_MEMORY_BARRIER ()

vppinfra: refactor use of CLIB_MEMORY_BARRIER ()

All instances of test_and_set locks used the following sequence
to release the locks:

CLIB_MEMORY_BARRIER ();
p->lock = 0; // p is a generic struct with a TAS lock

Use clib_atomic_release to generate more efficient assembly code.

Type: refactor

Change-Id: Idca3a38b1cf43578108bdd1afe83b6ebc17a4c68
Signed-off-by: Jason Zhang <jason.zhang2@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Lijian Zhang <Lijian.Zhang@arm.com>