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/pagewalk.c b/mm/pagewalk.c
index b4f27d2..1cf1417 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -77,11 +77,11 @@
 
 /**
  * walk_page_range - walk a memory map's page tables with a callback
- * @mm - memory map to walk
- * @addr - starting address
- * @end - ending address
- * @walk - set of callbacks to invoke for each level of the tree
- * @private - private data passed to the callback function
+ * @mm: memory map to walk
+ * @addr: starting address
+ * @end: ending address
+ * @walk: set of callbacks to invoke for each level of the tree
+ * @private: private data passed to the callback function
  *
  * Recursively walk the page table for the memory area in a VMA,
  * calling supplied callbacks. Callbacks are called in-order (first