timer: protect initialization with lock

timer: protect initialization with lock

rte_timer_subsystem_initialized is a global variable that can be
accessed by multiple processes simultaneously. Hence, any access
to rte_timer_subsystem_initialized should be protected by
rte_mcfg_timer_lock.

Fixes: f9d6cd8bfe9e ("timer: fix resource leak in finalize")
Cc: stable@dpdk.org
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
Acked-by: Erik Gabriel Carrillo <erik.g.carrillo@intel.com>