platform/x86: asus-nb-wmi: Allow configuring SW_TABLET_MODE method with a module option

Unfortunately we have been unable to find a reliable way to detect if
and how SW_TABLET_MODE reporting is supported, so we are relying on
DMI quirks for this.

Add a module-option to specify the SW_TABLET_MODE method so that this can
be easily tested without needing to rebuild the kernel.

BugLink: https://gitlab.freedesktop.org/libinput/libinput/-/issues/639


Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210812145513.39117-1-hdegoede@redhat.com