nvc0: disable primitive restart and index bias during blits

nvc0: disable primitive restart and index bias during blits

Back in the dawn of time, we used to do immediate uploads for the vertex
data, and all was well. However Maxwell dropped support for immediate
vertex data, so we started feeding in a VBO (in all cases). But we
forgot to disable some things that apply in such cases, specifically
primitive restart and index bias. The latter was causing WoW and other
Blizzard games trouble as they use a pattern where they draw with a base
vertex (aka index bias), followed by texture uploads (aka blits,
internally).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91526
Cc: "11.1 11.2" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Tested-by: Karol Herbst <nouveau@karolherbst.de>