HID: elan: Fix potential double free in elan_input_configured

'input' is a managed resource allocated with devm_input_allocate_device(),
so there is no need to call input_free_device() explicitly or
there will be a double free.

According to the doc of devm_input_allocate_device():
 * Managed input devices do not need to be explicitly unregistered or
 * freed as it will be done automatically when owner device unbinds from
 * its driver (or binding fails).

Fixes: b7429ea5 ("HID: elan: Fix memleak in elan_input_configured")
Fixes: 9a6a4193 ("HID: Add driver for USB ELAN Touchpad")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>