radv: fix draw calls with 0-sized index buffers and robustness on NAVI10

The correct workaround is to bind an internal index buffer to handle
robustness2 correctly.

Fixes dEQP-VK.robustness.index_access.* in CTS 1.3.5.0 on NAVI10.

Cc: mesa-stable
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21471>
(cherry picked from commit c356f1b4edc942f8c62125d01b7ddb886b72bbb7)
2 files changed