spi: davinci: fix spurious i/o error

davinci_spi_bufs() uses wait_for_completion_interruptible()
without bothering to handle -ERESTARTSYS. Due to this,
sometime, it returns prematurely when a signal is received.
Since the return value is never checked, userspace eventually
receives a spurious -EIO.

To fix this, use un-interruptible wait_for_completion_timeout().
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-davinci.c

@@ -703,7 +703,8 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t)
 
 	/* Wait for the transfer to complete */
 	if (spicfg->io_type != SPI_IO_TYPE_POLL) {
-		wait_for_completion_interruptible(&(dspi->done));
+		if (wait_for_completion_timeout(&dspi->done, HZ) == 0)
+			errors = SPIFLG_TIMEOUT_MASK;
 	} else {
 		while (dspi->rcount > 0 || dspi->wcount > 0) {
 			errors = davinci_spi_process_events(dspi);