platform/x86: panasonic-laptop: don't report duplicate brightness key-presses

The brightness key-presses might also get reported by the ACPI video bus,
check for this and in this case don't report the presses to avoid reporting
2 presses for a single key-press.

Fixes: ed83c917 ("platform/x86: panasonic-laptop: Resolve hotkey double trigger bug")
Reported-and-tested-by: Stefan Seyfried <seife+kernel@b1-systems.com>
Reported-and-tested-by: Kenneth Chan <kenneth.t.chan@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220624112340.10130-6-hdegoede@redhat.com