s390/dasd: Use kzalloc instead of kmalloc/memset

Use kzalloc rather than duplicating its implementation, which
makes code simple and easy to understand.

Signed-off-by: Haowen Bai <[e-mail]>
Reviewed-by: Sven Schnelle <[e-mail]>
Signed-off-by: Stefan Haberland <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jens Axboe <[e-mail]>

drivers/s390/block/dasd_eckd.c

···
 {
 	struct pe_handler_work_data *data;
 
-	data = kmalloc(sizeof(*data), GFP_ATOMIC | GFP_DMA);
+	data = kzalloc(sizeof(*data), GFP_ATOMIC | GFP_DMA);
 	if (!data) {
 		if (mutex_trylock(&dasd_pe_handler_mutex)) {
 			data = pe_handler_worker;
···
 		} else {
 			return -ENOMEM;
 		}
-	} else {
-		memset(data, 0, sizeof(*data));
-		data->isglobal = 0;
 	}
 	INIT_WORK(&data->worker, do_pe_handler_work);
 	dasd_get_device(device);