vmalloc: add @align to vm_area_register_early()

Impact: allow larger alignment for early vmalloc area allocation

Some early vmalloc users might want larger alignment, for example, for
custom large page mapping.  Add @align to vm_area_register_early().
While at it, drop docbook comment on non-existent @size.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
diff --git a/mm/percpu.c b/mm/percpu.c
index ed92caa..41e7a5f 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -860,7 +860,7 @@
 	/* init and register vm area */
 	static_vm.flags = VM_ALLOC;
 	static_vm.size = pcpu_chunk_size;
-	vm_area_register_early(&static_vm);
+	vm_area_register_early(&static_vm, PAGE_SIZE);
 
 	/* init static_chunk */
 	static_chunk = alloc_bootmem(pcpu_chunk_struct_size);