fpga: dfl: fme: add DFL_FPGA_FME_PORT_RELEASE/ASSIGN ioctl support.

fpga: dfl: fme: add DFL_FPGA_FME_PORT_RELEASE/ASSIGN ioctl support.

In order to support virtualization usage via PCIe SRIOV, this patch
adds two ioctls under FPGA Management Engine (FME) to release and
assign back the port device. In order to safely turn Port from PF
into VF and enable PCIe SRIOV, it requires user to invoke this
PORT_RELEASE ioctl to release port firstly to remove userspace
interfaces, and then configure the PF/VF access register in FME.
After disable SRIOV, it requires user to invoke this PORT_ASSIGN
ioctl to attach the port back to PF.

 Ioctl interfaces:
 * DFL_FPGA_FME_PORT_RELEASE
   Release platform device of given port, it deletes port platform
   device to remove related userspace interfaces on PF. After this
   function, then it's safe to configure PF/VF access mode to VF,
   and enable VFs via SRIOV.

 * DFL_FPGA_FME_PORT_ASSIGN
   Assign platform device of given port back to PF. After configure
   PF/VF access mode to PF, this ioctl adds port platform device
   back to re-enable related userspace interfaces on PF.

Signed-off-by: Zhang Yi Z <yi.z.zhang@intel.com>
Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Acked-by: Alan Tull <atull@kernel.org>
Acked-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Link: https://lore.kernel.org/r/1564914022-3710-2-git-send-email-hao.wu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>