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 <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/touchscreen/atmel_mxt_ts.c

···
 #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>