nvk: Upload shaders using the DMA engine
NVIDIA GPUs before Ampere don't have resizable BAR support, meaning that we're restricted to 256MB of mappable VRAM globally. Anything outside of this and the kernel has to start evicting things, which isn't as reliable as one might like. This MR refactors the driver to upload shaders via the DMA engine, saving that prescious BAR space for other uses.
Edited by Faith Ekstrand