percpu: Make pcpu_setup_first_chunk() void function

pcpu_setup_first_chunk() will panic or BUG_ON if the are some
error and doesn't return any error, hence it can be defined to
return void.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
[Dennis: fixed kbuild warning for pcpu_page_first_chunk()]
diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c
index 05490dd..004dee2 100644
--- a/arch/ia64/mm/discontig.c
+++ b/arch/ia64/mm/discontig.c
@@ -245,10 +245,7 @@ void __init setup_per_cpu_areas(void)
 		gi->cpu_map		= &cpu_map[unit];
 	}
 
-	rc = pcpu_setup_first_chunk(ai, base);
-	if (rc)
-		panic("failed to setup percpu area (err=%d)", rc);
-
+	pcpu_setup_first_chunk(ai, base);
 	pcpu_free_alloc_info(ai);
 }
 #endif