NFSD: Use DEFINE_SPINLOCK() for spinlock

spinlock can be initialized automatically with DEFINE_SPINLOCK()
rather than explicitly calling spin_lock_init().
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Guobin Huang <huangguobin4@huawei.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfssvc.c

@@ -84,7 +84,7 @@ DEFINE_MUTEX(nfsd_mutex);
  * version 4.1 DRC caches.
  * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage.
  */
-spinlock_t	nfsd_drc_lock;
+DEFINE_SPINLOCK(nfsd_drc_lock);
 unsigned long	nfsd_drc_max_mem;
 unsigned long	nfsd_drc_mem_used;
 
@@ -563,7 +563,6 @@ static void set_max_drc(void)
 	nfsd_drc_max_mem = (nr_free_buffer_pages()
 					>> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE;
 	nfsd_drc_mem_used = 0;
-	spin_lock_init(&nfsd_drc_lock);
 	dprintk("%s nfsd_drc_max_mem %lu \n", __func__, nfsd_drc_max_mem);
 }