ASpeed DRM Driver Adding DMA-BUF/PRIME Sharing For Use With Servers Having dGPUs

[tle]

"This patch is designed to solve the problem that the AST is not displayed when the server plug in a discrete graphics card at the same time. We call the dirty callback function to copy the rendering results of the discrete graphics card to the ast side by dma-buf."

Source: https://www.phoronix.com/news/AST-DMA-BUF-PRIME-Sharing