wic: Introduce the --use-label partition parameter

We can use this parameter to make the wic use the label to name a
partition in /etc/fstab.

(From OE-Core rev: 51638edaa00befaed58e2def255d46ae44d9234f)

Signed-off-by: Kevin Hao <kexin.hao@windriver.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/partition.py

@@ -47,6 +47,7 @@ class Partition():
         self.fsopts = args.fsopts
         self.fstype = args.fstype
         self.label = args.label
+        self.use_label = args.use_label
         self.mkfs_extraopts = args.mkfs_extraopts
         self.mountpoint = args.mountpoint
         self.no_table = args.no_table