rtd2132: Add driver for Realtek RTD2132 LVDS bridge

This driver allows the mainboard to enable spread spectrum
clocking at 0.5%, 1.0%, and 1.5% with devicetree settings.

Change-Id: I59c61e67aa8e951fd9904ad951deb6d0ba29669e
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/61894
Reviewed-on: http://review.coreboot.org/4365
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Tested-by: build bot (Jenkins)
diff --git a/src/drivers/i2c/Kconfig b/src/drivers/i2c/Kconfig
index 4eb3f3f..a6f59f4 100644
--- a/src/drivers/i2c/Kconfig
+++ b/src/drivers/i2c/Kconfig
@@ -4,5 +4,6 @@
 source src/drivers/i2c/i2cmux/Kconfig
 source src/drivers/i2c/i2cmux2/Kconfig
 source src/drivers/i2c/lm63/Kconfig
+source src/drivers/i2c/rtd2132/Kconfig
 source src/drivers/i2c/w83795/Kconfig
 source src/drivers/i2c/w83793/Kconfig