dm: i2c: Add a migration method for I2C

This probably should have been done a while back since it is a core
system. Add a migration deadline of later this year, to catch the
stragglers.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index c6a3983..e9b9c15 100644
--- a/Makefile
+++ b/Makefile
@@ -1096,6 +1096,7 @@
 	$(call deprecated,CONFIG_WDT,DM watchdog,v2019.10,\
 		$(CONFIG_WATCHDOG)$(CONFIG_HW_WATCHDOG))
 	$(call deprecated,CONFIG_DM_ETH,Ethernet drivers,v2020.07,$(CONFIG_NET))
+	$(call deprecated,CONFIG_DM_I2C,I2C drivers,v2022.04,$(CONFIG_I2C))
 	@# Check that this build does not use CONFIG options that we do not
 	@# know about unless they are in Kconfig. All the existing CONFIG
 	@# options are whitelisted, so new ones should not be added.