backlight: tdo24m: ensure chip select changes between transfers

Some SPI host drivers do not change chip select betwen transfers unless
.cs_chnage field is explicitly set. The LCD spec requires chip select
change between consecuitive transfers, so ensure it at the SPI driver
level.
Signed-off-by: NMike Rapoport <mike@compulab.co.il>
Signed-off-by: NEric Miao <eric.y.miao@gmail.com>

drivers/video/backlight/tdo24m.c

@@ -367,6 +367,7 @@ static int __devinit tdo24m_probe(struct spi_device *spi)
 
 	spi_message_init(m);
 
+	x->cs_change = 1;
 	x->tx_buf = &lcd->buf[0];
 	spi_message_add_tail(x, m);