FPGA Enumeration Failure

I am connecting Arria 10 Programmable Acceleration card to Hifive Sifive Unmatched Board through PCI Express.I am booting up RISC-V CPU using ubuntu.I am able to list the FPGA device connected through lspci.I am facing enumeration failure error at boot time.I am attaching the screenshot of error.
Kindly provide solution to the problem