spi: bfin5xx: fix build error

should include linux/gpio.h

Signed-off-by: Steven Miao <realmz6@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-bfin5xx.c

@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/device.h>
+#include <linux/gpio.h>
 #include <linux/slab.h>
 #include <linux/io.h>
 #include <linux/ioport.h>