mm/vmalloc.c: fix a warning while make xmldocs

This patch fixes following warning while "make xmldocs"

  mm/vmalloc.c:1877: warning: Excess function parameter 'prot' description in 'vm_map_ram'

This warning started since commit d4efd79a ("mm: remove the prot
argument from vm_map_ram").

Link: http://lkml.kernel.org/r/20200622152850.140871-1-standby24x7@gmail.com
Fixes: d4efd79a ("mm: remove the prot argument from vm_map_ram")
Signed-off-by: Masanari Iida <standby24x7@gmail.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/vmalloc.c

@@ -1862,7 +1862,6 @@ EXPORT_SYMBOL(vm_unmap_ram);
  * @pages: an array of pointers to the pages to be mapped
  * @count: number of pages
  * @node: prefer to allocate data structures on this node
- * @prot: memory protection to use. PAGE_KERNEL for regular RAM
  *
  * If you use this function for less than VMAP_MAX_ALLOC pages, it could be
  * faster than vmap so it's good.  But if you mix long-life and short-life