spi: gpio: Include linux/of.h header

'of_match_ptr' is defined in linux/of.h. Include it explicitly.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-gpio.c

@@ -22,6 +22,7 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/gpio.h>
+#include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/of_gpio.h>