spi: Add call to spi_slave_abort() function when spidev driver is released

This change is necessary for spidev devices (e.g. /dev/spidev3.0) working
in the slave mode (like NXP's dspi driver for Vybrid SoC).

When SPI HW works in this mode - the master is responsible for providing
CS and CLK signals. However, when some fault happens - like for example
distortion on SPI lines - the SPI Linux driver needs a chance to recover
from this abnormal situation and prepare itself for next (correct)
transmission.

This change doesn't pose any threat on drivers working in master mode as
spi_slave_abort() function checks if SPI slave mode is supported.
Signed-off-by: Lukasz Majewski <lukma@denx.de>
Link: https://lore.kernel.org/r/20190924110547.14770-2-lukma@denx.deSigned-off-by: Mark Brown <broonie@kernel.org>
Reported-by: kbuild test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20190925091143.15468-2-lukma@denx.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spidev.c

@@ -627,6 +627,9 @@ static int spidev_release(struct inode *inode, struct file *filp)
 		if (dofree)
 			kfree(spidev);
 	}
+#ifdef CONFIG_SPI_SLAVE
+	spi_slave_abort(spidev->spi);
+#endif
 	mutex_unlock(&device_list_lock);
 
 	return 0;