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: NYang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20210601120721.3198488-1-yangyingliang@huawei.comSigned-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi-mem.c

@@ -896,7 +896,7 @@ int spi_mem_driver_register_with_owner(struct spi_mem_driver *memdrv,
 EXPORT_SYMBOL_GPL(spi_mem_driver_register_with_owner);
 
 /**
- * spi_mem_driver_unregister_with_owner() - Unregister a SPI memory driver
+ * spi_mem_driver_unregister() - Unregister a SPI memory driver
  * @memdrv: the SPI memory driver to unregister
  *
  * Unregisters a SPI memory driver.