mm: kernel-doc: add missing parameter descriptions

Link: http://lkml.kernel.org/r/1519585191-10180-4-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/pagewalk.c

@@ -258,6 +258,9 @@ static int __walk_page_range(unsigned long start, unsigned long end,
 
 /**
  * walk_page_range - walk page table with caller specific callbacks
+ * @start: start address of the virtual address range
+ * @end: end address of the virtual address range
+ * @walk: mm_walk structure defining the callbacks and the target address space
  *
  * Recursively walk the page table tree of the process represented by @walk->mm
  * within the virtual address range [@start, @end). During walking, we can do