UBI: re-name set volume properties ioctl

Rename the ioctl which sets volume properties from 'UBI_IOCSETPROP' to
'UBI_IOCSETVOLPROP' to reflect the fact that this ioctl is about volume
properties, not device properties. This is also consistent with the
other volume ioctl name - 'UBI_IOCVOLUP'.

The main motivation for the re-name, however, is that we are going
to introduce the per-UBI device "set properties" ioctl, so we need
good and logical naming.

At the same time, re-name the "set volume properties request" data
structure from 'struct ubi_set_prop_req' to
'struct ubi_set_vol_prop_req'.

And re-name 'UBI_PROP_DIRECT_WRITE' to 'UBI_VOL_PROP_DIRECT_WRITE'.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 9a17032..4119cb8 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -561,18 +561,18 @@
 	}
 
 	/* Set volume property command */
-	case UBI_IOCSETPROP:
+	case UBI_IOCSETVOLPROP:
 	{
-		struct ubi_set_prop_req req;
+		struct ubi_set_vol_prop_req req;
 
 		err = copy_from_user(&req, argp,
-				sizeof(struct ubi_set_prop_req));
+				     sizeof(struct ubi_set_vol_prop_req));
 		if (err) {
 			err = -EFAULT;
 			break;
 		}
 		switch (req.property) {
-		case UBI_PROP_DIRECT_WRITE:
+		case UBI_VOL_PROP_DIRECT_WRITE:
 			mutex_lock(&ubi->device_mutex);
 			desc->vol->direct_writes = !!req.value;
 			mutex_unlock(&ubi->device_mutex);