Input: edt-ft5x06 - add a missing condition

The if condition was accidentally deleted here so we return every time
instead of returning on error.

Fixes: fd335ab0

 ('Input: edt-ft5x06 - add support for M09 firmware version')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>
Acked-By: Lothar Waßmann <LW@KARO-electronics.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>