docbook: fix vmalloc missing parameter notation

Fix vmalloc kernel-doc warning:

Warning(linux-2.6.25-git14//mm/vmalloc.c:555): No description found for parameter 'caller'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 2a39cf1..6e45b0f 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -547,6 +547,7 @@
  *	@gfp_mask:	flags for the page level allocator
  *	@prot:		protection mask for the allocated pages
  *	@node:		node to use for allocation or -1
+ *	@caller:	caller's return address
  *
  *	Allocate enough pages to cover @size from the page level
  *	allocator with @gfp_mask flags.  Map them into contiguous