mesa: recover target_check before get_current_tex_objects
At compressed_tex_sub_image we only can obtain the tex_object after compressed_subtexture_target_check is validated for TEX_MODE_CURRENT. So if the target is wrong the error is raised to the user.
This completes the fix for the regression introduced on "mesa: refactor compressed_tex_sub_image function" of MR !1612 (merged) so following tests pass again:
dEQP-GLES3.functional.negative_api.texture.compressedtexsubimage3d dEQP-GLES31.functional.debug.negative_coverage.get_error.texture.compressedtexsubimage3d
Fixes: 7df233d6 ("mesa: refactor compressed_tex_sub_image function")