mm: fix various kernel-doc comments

Fix various kernel-doc notation in mm/:

filemap.c: add function short description; convert 2 to kernel-doc
fremap.c: change parameter 'prot' to @prot
pagewalk.c: change "-" in function parameters to ":"
slab.c: fix short description of kmem_ptr_validate()
swap.c: fix description & parameters of put_pages_list()
swap_state.c: fix function parameters
vmalloc.c: change "@returns" to "Returns:" since that is not a parameter

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>

mm/swap.c

@@ -78,12 +78,11 @@ void put_page(struct page *page)
 EXPORT_SYMBOL(put_page);
 
 /**
- * put_pages_list(): release a list of pages
+ * put_pages_list() - release a list of pages
+ * @pages: list of pages threaded on page->lru
  *
  * Release a list of pages which are strung together on page.lru.  Currently
  * used by read_cache_pages() and related error recovery code.
- *
- * @pages: list of pages threaded on page->lru
  */
 void put_pages_list(struct list_head *pages)
 {