spi: dw: Initialize of_node to discover DT node children

The of_node element must be initialized to enable discovery of node
children which takes place in the of_register_spi_devices() function.

Signed-off-by: Thor Thayer <tthayer@opensource.altera.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 7292158..72e12ba 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -669,6 +669,7 @@
 	master->cleanup = dw_spi_cleanup;
 	master->transfer_one_message = dw_spi_transfer_one_message;
 	master->max_speed_hz = dws->max_freq;
+	master->dev.of_node = dev->of_node;
 
 	/* Basic HW init */
 	spi_hw_init(dws);