touchscreen: Fix build of da9034

Missing an include and thus breaks the x86-64 build.
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/input/touchscreen/da9034-ts.c

@@ -16,6 +16,7 @@
 #include <linux/delay.h>
 #include <linux/platform_device.h>
 #include <linux/input.h>
+#include <linux/workqueue.h>
 #include <linux/mfd/da903x.h>
 
 #define DA9034_MANUAL_CTRL	0x50