mtip32xx: use DEFINE_SPINLOCK() for spinlock

spinlock can be initialized automatically with DEFINE_SPINLOCK()
rather than explicitly calling spin_lock_init().

Signed-off-by: Shixin Liu <liushixin2@huawei.com>
Link: https://lore.kernel.org/r/20210329095349.4170870-1-liushixin2@huawei.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>