platform/x86: lg-laptop: Use correct event for touchpad toggle FN-key

Send F21 which is the standard for this key, instead of F13.

Signed-off-by: Matan Ziv-Av <matan@svgalib.org>
Link: https://lore.kernel.org/r/b847895c1f170e2e59df5757a4d603d28149f648.1629291912.git.matan@svgalib.org


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