package/sunxi-mali: use git submodules

package/sunxi-mali: use git submodules

The sunxi-mali git tree is set up with a submodule that contains the
actual libraries. Since there was no support for git submodules so far,
we used a dirty trick to have that submodule cloned by its own package,
with sunxi-mali just vampirising it into its own build dir.

Now that we have support for git submodules, we can simplify stuff a
bit, and have sunxi-mali directly download the proprietary libs itself.

Remove the .hash file since we're not checking hashes for git clones.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>