udev-extraconf/mount.sh: add LABELs to mountpoints

udev-extraconf/mount.sh: add LABELs to mountpoints

This alters the mountpoints such that if a device has a LABEL or
a PARTLABEL, it will be mounted at e.g.:

  /run/media/$LABEL-<device-node>
  /run/media/$PARTLABEL-<device-node>
  /run/media/rootfs-sda2

otherwise the device will be mounted at e.g.:

  /run/media/<device-node>
  /run/media/sda1

The <device-node> appended with LABEL or PARTLABEL makes sure that
the mountpoint is unique, therefore, avoids overlapping mounts.

Signed-off-by: Arsalan H. Awan <Arsalan_Awan@mentor.com>
Signed-off-by: Muhammad Hamza <muhammad_hamza@mentor.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>