mb/google/rex/var/kanix: Add Fn key scancode

The Fn key on kanix emits the scancode 94 (0x5e).

BUG=b:384580437
TEST=Build and test on kanix, the fn key works normally

Change-Id: Ia693813dafe1bd35840dfb892827598a7ca9c88f
Signed-off-by: Tyler Wang <tyler.wang@quanta.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/85438
Reviewed-by: Ren Kuo <ren.kuo@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>

src/mainboard/google/rex/Kconfig

@@ -71,6 +71,7 @@ config BOARD_GOOGLE_MODEL_KANIX
 	def_bool n
 	select BOARD_GOOGLE_BASEBOARD_REX
 	select DRIVERS_GENERIC_ALC1015
+	select MAINBOARD_HAS_GOOGLE_STRAUSS_KEYBOARD
 	select RT8168_GEN_ACPI_POWER_RESOURCE
 	select RT8168_GET_MAC_FROM_VPD
 	select RT8168_SET_LED_MODE