Input: adp5588-keys - cancel workqueue in failure path

In case we start with the device not fully quiesced we should make sure we
cancel the workqueue after freeing interrupt.

Signed-off-by: Pramod Gurav <pramod.gurav@smartplayin.com>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>