fpga: zynqmp-fpga: Address warning about unused variable

warning: ‘zynqmp_fpga_of_match’ defined but not used
 [-Wunused-const-variable=]
 static const struct of_device_id zynqmp_fpga_of_match[] = {

Fixes: c09f7471 ("fpga manager: Adding FPGA Manager support for Xilinx zynqmp")
Cc: Tom Rix <trix@redhat.com>
Signed-off-by: Moritz Fischer <mdf@kernel.org>