pid: kill pidhash_size in pidhash_init()

After commit 3d375d78593c ("mm: update callers to use HASH_ZERO flag"),
drop unused pidhash_size in pidhash_init().

Link: http://lkml.kernel.org/r/1500389267-49222-1-git-send-email-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Pavel Tatashin <Pasha.Tatashin@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/pid.c

@@ -575,13 +575,10 @@ struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
  */
 void __init pidhash_init(void)
 {
-	unsigned int pidhash_size;
-
 	pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18,
 					   HASH_EARLY | HASH_SMALL | HASH_ZERO,
 					   &pidhash_shift, NULL,
 					   0, 4096);
-	pidhash_size = 1U << pidhash_shift;
 }
 
 void __init pidmap_init(void)