[PATCH -next] input/touchscreen: add header file to fix ad7879.c build errors

[Randy Dunlap]

From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

Add header file to fix these build errors:

../drivers/input/touchscreen/ad7879.c: In function 'ad7879_parse_dt':
../drivers/input/touchscreen/ad7879.c:505:2: error: implicit declaration of function 'device_property_read_u32' [-Werror=implicit-function-declaration]
  err = device_property_read_u32(dev, "adi,resistance-plate-x", &tmp);
  ^
../drivers/input/touchscreen/ad7879.c:512:2: error: implicit declaration of function 'device_property_read_u8' [-Werror=implicit-function-declaration]
  device_property_read_u8(dev, "adi,first-conversion-delay",
  ^
../drivers/input/touchscreen/ad7879.c:521:2: error: implicit declaration of function 'device_property_read_bool' [-Werror=implicit-function-declaration]
  ts->swap_xy = device_property_read_bool(dev, "touchscreen-swapped-x-y");
  ^

Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc:	Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Cc:	linux-input@xxxxxxxxxxxxxxx
Cc:	Michael Hennerich <michael.hennerich@xxxxxxxxxx>
---
 drivers/input/touchscreen/ad7879.c |    1 +
 1 file changed, 1 insertion(+)

--- linux-next-20170224.orig/drivers/input/touchscreen/ad7879.c
+++ linux-next-20170224/drivers/input/touchscreen/ad7879.c
@@ -26,6 +26,7 @@
 #include <linux/input.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/property.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/gpio.h>