platform/x86: asus-tf103c-dock: Constify toprow keymap

This structure is never modified, make it const.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230130-hid-const-ll-driver-v1-8-3fc282b3b1d0@weissschuh.net


Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>