spi: zynq-qspi: Fix missing spi_unregister_controller when unload module

Use devm_spi_register_controller to fix missing spi_unregister_controller
when unload module.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/20190818095113.2397-1-axel.lin@ingics.com


Signed-off-by: Mark Brown <broonie@kernel.org>