Input: atmel_mxt_ts - fix multiple <linux/property.h> includes

Both v4.16-rc7 commit 93afb1d6e72a ("Input: atmel_mxt_ts - switch from
OF to generic device properties") and v4.16-rc7 commit 96a938aa214e
("Input: atmel_mxt_ts - remove platform data support") added includes of
"<linux/property.h>".  Remove one of the duplicate includes to fix this.

Signed-off-by: George G. Davis <george_davis@mentor.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/atmel_mxt_ts.c

@@ -29,7 +29,6 @@
 #include <linux/property.h>
 #include <linux/slab.h>
 #include <linux/gpio/consumer.h>
-#include <linux/property.h>
 #include <asm/unaligned.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-ioctl.h>