fpga: lattice-sysconfig-spi: simplify with spi_get_device_match_data()

Use spi_get_device_match_data() helper to simplify a bit the driver.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/20260510090556.1582900-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>