[SCSI] zfcp: Use memdup_user and kstrdup

Use the functions memdup_user and kstrdup to allocate memory and copy
the data in one step, saving some lines of code.

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index 6e9c7f3..7c01c4c 100644
--- a/drivers/s390/scsi/zfcp_aux.c
+++ b/drivers/s390/scsi/zfcp_aux.c
@@ -98,13 +98,11 @@
 	u64 wwpn, lun;
 
 	/* duplicate devstr and keep the original for sysfs presentation*/
-	str_saved = kmalloc(strlen(devstr) + 1, GFP_KERNEL);
+	str_saved = kstrdup(devstr, GFP_KERNEL);
 	str = str_saved;
 	if (!str)
 		return;
 
-	strcpy(str, devstr);
-
 	token = strsep(&str, ",");
 	if (!token || strlen(token) >= ZFCP_BUS_ID_SIZE)
 		goto err_out;