tcp: suppress a division by zero warning

Andrew Morton reported following warning on one ARM build
with gcc-4.4 :

net/ipv4/inet_hashtables.c: In function 'inet_ehash_locks_alloc':
net/ipv4/inet_hashtables.c:617: warning: division by zero

Even guarded with a test on sizeof(spinlock_t), compiler does not
like current construct on a !CONFIG_SMP build.

Remove the warning by using a temporary variable.

Fixes: 095dc8e0 ("tcp: fix/cleanup inet_ehash_locks_alloc()")
Reported-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/inet_hashtables.c

@@ -624,22 +624,21 @@ EXPORT_SYMBOL_GPL(inet_hashinfo_init);
 
 int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
 {
+	unsigned int locksz = sizeof(spinlock_t);
 	unsigned int i, nblocks = 1;
 
-	if (sizeof(spinlock_t) != 0) {
+	if (locksz != 0) {
 		/* allocate 2 cache lines or at least one spinlock per cpu */
-		nblocks = max_t(unsigned int,
-				2 * L1_CACHE_BYTES / sizeof(spinlock_t),
-				1);
+		nblocks = max(2U * L1_CACHE_BYTES / locksz, 1U);
 		nblocks = roundup_pow_of_two(nblocks * num_possible_cpus());
 
 		/* no more locks than number of hash buckets */
 		nblocks = min(nblocks, hashinfo->ehash_mask + 1);
 
-		hashinfo->ehash_locks =	kmalloc_array(nblocks, sizeof(spinlock_t),
+		hashinfo->ehash_locks =	kmalloc_array(nblocks, locksz,
 						      GFP_KERNEL | __GFP_NOWARN);
 		if (!hashinfo->ehash_locks)
-			hashinfo->ehash_locks = vmalloc(nblocks * sizeof(spinlock_t));
+			hashinfo->ehash_locks = vmalloc(nblocks * locksz);
 
 		if (!hashinfo->ehash_locks)
 			return -ENOMEM;