PM: hibernate: swap: Use vzalloc() and kzalloc()

Replace vmalloc()/memset() with vzalloc() and kmalloc()/memset() with
kzalloc() to simplify the code.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>