ARM: S3C64XX: Add linux/export.h to dev-spi.c

This is required for the EXPORT_SYMBOL()s the code uses, previously the
header was being included implicitly by another header.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/mach-s3c64xx/dev-spi.c

@@ -10,6 +10,7 @@
 
 #include <linux/kernel.h>
 #include <linux/string.h>
+#include <linux/export.h>
 #include <linux/platform_device.h>
 #include <linux/dma-mapping.h>
 #include <linux/gpio.h>