fpga_qpn was assigned but never used and compilation with W=1
produced the following warning:
drivers/net/ethernet/mellanox/mlx5/core/fpga/core.c: In function _mlx5_fpga_event_:
drivers/net/ethernet/mellanox/mlx5/core/fpga/core.c:320:6: warning:
variable _fpga_qpn_ set but not used [-Wunused-but-set-variable]
u32 fpga_qpn;
^~~~~~~~