spi: spi-mem: fix doc warning in spi-mem.c

Fix the following make W=1 warning:

  drivers/spi/spi-mem.c:819: warning: expecting prototype for spi_mem_driver_unregister_with_owner(). Prototype was for spi_mem_driver_unregister() instead

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20210601120721.3198488-1-yangyingliang@huawei.com


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