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>
diff --git a/mm/slab.c b/mm/slab.c
index e6c698f..bb4070e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3624,12 +3624,11 @@
 EXPORT_SYMBOL(kmem_cache_alloc);
 
 /**
- * kmem_ptr_validate - check if an untrusted pointer might
- *	be a slab entry.
+ * kmem_ptr_validate - check if an untrusted pointer might be a slab entry.
  * @cachep: the cache we're checking against
  * @ptr: pointer to validate
  *
- * This verifies that the untrusted pointer looks sane:
+ * This verifies that the untrusted pointer looks sane;
  * it is _not_ a guarantee that the pointer is actually
  * part of the slab cache in question, but it at least
  * validates that the pointer can be dereferenced and