Use git submodule fetcher
Use git submodule fetcher

Use git submodule fetcher instead of calling git submodule manually.
This fixes a phase error (downloading the sources should happen in fetch
task instead of configure task) and helps with proxies.

Signed-off-by: Ismo Puustinen <75dda586a9213f0e0695eb79120c94222bb30e60@intel.com>

solettaproject/meta-soletta,solettaproject/meta-soletta,brunobottazzini/meta-soletta,brunobottazzini/meta-soletta