vmalloc: remove KM_USER0 from comments

Signed-off-by: Cong Wang <amwang@redhat.com>

mm/vmalloc.c

@@ -1975,9 +1975,7 @@ static int aligned_vwrite(char *buf, char *addr, unsigned long count)
  *	IOREMAP area is treated as memory hole and no copy is done.
  *
  *	If [addr...addr+count) doesn't includes any intersects with alive
- *	vm_struct area, returns 0.
- *	@buf should be kernel's buffer. Because	this function uses KM_USER0,
- *	the caller should guarantee KM_USER0 is not used.
+ *	vm_struct area, returns 0. @buf should be kernel's buffer.
  *
  *	Note: In usual ops, vread() is never necessary because the caller
  *	should know vmalloc() area is valid and can use memcpy().
@@ -2051,9 +2049,7 @@ finished:
  *	IOREMAP area is treated as memory hole and no copy is done.
  *
  *	If [addr...addr+count) doesn't includes any intersects with alive
- *	vm_struct area, returns 0.
- *	@buf should be kernel's buffer. Because	this function uses KM_USER0,
- *	the caller should guarantee KM_USER0 is not used.
+ *	vm_struct area, returns 0. @buf should be kernel's buffer.
  *
  *	Note: In usual ops, vwrite() is never necessary because the caller
  *	should know vmalloc() area is valid and can use memcpy().