mesa/texformat: use format conversion function in _mesa_choose_tex_format

This function's cases for non-generic compressed formats duplicate
the GL to MESA translation in _mesa_glenum_to_compressed_format().
This patch replaces the switch cases with a call to the translation
function. This change teaches this function about ASTC, thus enabling
ASTC for glTex*Storage*() calls.

Reviewed-by: Chad Versace <chad.versace@intel.com>
Signed-off-by: Nanley Chery <nanley.g.chery@intel.com>
1 file changed