Input: i8042 - fix error return code in i8042_setup_aux()

Fix to return a negative error code from the error handling case
instead of 0 in function i8042_setup_aux(), as done elsewhere in this
function.

Fixes: f8113416

 ("Input: i8042 - use platform_driver_probe")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Luo Meng <luomeng12@huawei.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20201123133420.4071187-1-luomeng12@huawei.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>