extcon: extcon-max77693.c: Fix potential work-queue cancellation race

The extcon IRQ schedules a work item. IRQ is requested using devm while
WQ is cancelld at remove(). This mixing of devm and manual unwinding has
potential case where the WQ has been emptied (.remove() was ran) but
devm unwinding of IRQ was not yet done. It may be possible the IRQ is
triggered at this point scheduling new work item to the already flushed
queue.

According to the input documentation the input device allocated by
devm_input_allocate_device() does not need to be explicitly unregistered.
Use the new devm_work_autocancel() and remove the remove() to simplify the
code.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Link: https://lore.kernel.org/r/cbe8205eed8276f6e6db5003cfe51b8b0d4ac966.1623146580.git.matti.vaittinen@fi.rohmeurope.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>