image_types_tegra.bbclass: switch to tar.gz packaging
image_types_tegra.bbclass: switch to tar.gz packaging

With more tegraflash packages having to include ext4
filesystem image files, switch to creating a compressed
tarball instead of using zip for packaging.

This has two benefits:
1. Package creation is substantially faster, particularly
   when the package includes a raw ext4 image.
2. tar (unlike zip) understands sparse files and will
   preserve the sparseness.  Since the make-sdcard
   script now uses bmaptool if it can, keeping the
   ext4 filesystem image as a sparse file improves
   write speed substantially.

Signed-off-by: Matt Madison <1fa2ef4755a9226cb9a0a4840bd89b158ac71391@madison.systems>

madisongh/meta-tegra,madisongh/meta-tegra,madisongh/meta-tegra,madisongh/meta-tegra,madisongh/meta-tegra