spi/doc: spi_master_put must be followed up by kfree

Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

drivers/spi/spi.c

@@ -830,7 +830,8 @@ static struct class spi_master_class = {
  *
  * The caller is responsible for assigning the bus number and initializing
  * the master's methods before calling spi_register_master(); and (after errors
- * adding the device) calling spi_master_put() to prevent a memory leak.
+ * adding the device) calling spi_master_put() and kfree() to prevent a memory
+ * leak.
  */
 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
 {