bitbake: layerindex: Fix bitbake-layers layerindex-show-depends command

Running 'bitbake-layers layerindex-show-depends meta-filesystems' fails with:
```
Traceback (most recent call last):
  File "<...>/poky/bitbake/bin/bitbake-layers", line 93, in <module>
    ret = main()
  File "<...>/poky/bitbake/bin/bitbake-layers", line 86, in main
    return args.func(args)
  File "<...>/poky/bitbake/lib/bblayers/layerindex.py", line 209, in do_layerindex_show_depends
    self.do_layerindex_fetch(args)
  File "<...>/poky/bitbake/lib/bblayers/layerindex.py", line 182, in do_layerindex_fetch
    args.shallow)
AttributeError: 'Namespace' object has no attribute 'shallow'
```

Initialize the shallow attribute to fix it.

(Bitbake rev: 146cd25252ef065d09df0980b7dc670cb7e7b109)

Signed-off-by: Diego Sueiro <diego.sueiro@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

0 files changed, 0 insertions, 0 deletions