LSM: fix documentation for the syslog hook

The syslog hook was changed in the commit
"capabilities/syslog: open code cap_syslog logic to
fix build failure" (12b3052c). The argument @from_file
was removed from the hook. This patch updates the
documentation for the syslog hook accordingly.
Signed-off-by: Denis Efremov <efremov@ispras.ru>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

include/linux/lsm_hooks.h

@@ -1291,8 +1291,7 @@
  *	Check permission before accessing the kernel message ring or changing
  *	logging to the console.
  *	See the syslog(2) manual page for an explanation of the @type values.
- *	@type contains the type of action.
- *	@from_file indicates the context of action (if it came from /proc).
+ *	@type contains the SYSLOG_ACTION_* constant from <include/linux/syslog.h>
  *	Return 0 if permission is granted.
  * @settime:
  *	Check permission to change the system time.