Input: drv260x - fix input device's parent assignment

We were assigning I2C bus controller instead of client as parent device.
Besides being logically wrong, it messed up with devm handling of input
device. As a result we were leaving input device and event node behind
after rmmod-ing the driver, which lead to a kernel oops if one were to
access the event node later.

Let's remove the assignment and rely on devm_input_allocate_device() to
set it up properly for us.

Signed-off-by: Jingkui Wang <jkwang@google.com>
Fixes: 7132fe4f ("Input: drv260x - add TI drv260x haptics driver")
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>