google/leon: Add DRIVERS_I2C_RTD2132

This is LVDS bridge, I assume this was lost while upstreaming
or converting boards to variants.

Change-Id: I816a6b4035c4e935150cc77089c4224eee719c10
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35106
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>

src/mainboard/google/slippy/Kconfig

@@ -16,6 +16,7 @@ config BOARD_GOOGLE_BASEBOARD_SLIPPY
 	select INTEL_INT15
 	select MAINBOARD_HAS_LIBGFXINIT
 	select INTEL_GMA_HAVE_VBT
+	select DRIVERS_I2C_RTD2132 if BOARD_GOOGLE_LEON
 
 if BOARD_GOOGLE_BASEBOARD_SLIPPY