[RFC][VTA] Support for Cloud Devices (OpenCL-compatible)

Hi,

We want to use TVM for our ADM-PCIE-KU3 (Xilinx Kintex UltraScale) FPGA board. I wanted to ask if TVM support for server-class FPGAs (PCIe connected) is stable? Does it provide the required driver support?

@thierry @liangfu @zhanghaohit @hjiang