mtd: ubi: wire-up parent MTD device

Wire up the device parent pointer of UBI devices to their lower MTD
device, typically an MTD partition or whole-chip device.

The most noticeable change is that in sysfs, previously ubi devices
would be could in /sys/devices/virtual/ubi while after this change they
would be correctly attached to their parent MTD device, e.g.

/sys/devices/platform/1100d000.spi/spi_master/spi1/spi1.0/mtd/mtd2/ubi0.

Locating UBI devices using /sys/class/ubi/ of course still works as
well.

Signed-off-by: Daniel Golle <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

Author: dangowrt

drivers/mtd/ubi/build.c

@@ -915,6 +915,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 	ubi->dev.release = dev_release;
 	ubi->dev.class = &ubi_class;
 	ubi->dev.groups = ubi_dev_groups;
+	ubi->dev.parent = &mtd->dev;
 
 	ubi->mtd = mtd;
 	ubi->ubi_num = ubi_num;