platform/x86: intel-hid: Fix spurious wakeups caused by tablet-mode events during suspend

Some devices send (duplicate) tablet-mode events when moved around even
though the mode has not changed; and they do this even when suspended.

Change the tablet-mode event handling when priv->wakeup_mode is set to
update the switch state in case it changed and then return immediately
(without calling pm_wakeup_hard_event()) to avoid spurious wakeups.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=212537
Fixes: 537b0dd4

 ("platform/x86: intel-hid: Add support for SW_TABLET_MODE")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Elia Devito <eliadevito@gmail.com>
Link: https://lore.kernel.org/r/20210404143831.25173-1-hdegoede@redhat.com