PM: hibernate: Repair excess function parameter description warning

Function swsusp_close() does not have any parameters, so remove the
description of parameter @exclusive to prevent this warning.

swap.c:1573: warning: Excess function parameter 'exclusive' description in 'swsusp_close'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
[ rjw: Subject edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>