keyboard: Add a migration message

A few boards still use the old keyboard mechanism. Set a deadline for them
to update to driver model.
Signed-off-by: NSimon Glass <sjg@chromium.org>

Makefile

@@ -1123,6 +1123,7 @@ endif
 		$(CONFIG_WATCHDOG)$(CONFIG_HW_WATCHDOG))
 	$(call deprecated,CONFIG_DM_ETH,Ethernet drivers,v2020.07,$(CONFIG_NET))
 	$(call deprecated,CONFIG_DM_I2C,I2C drivers,v2022.04,$(CONFIG_SYS_I2C_LEGACY))
+	$(call deprecated,CONFIG_DM_KEYBOARD,Keyboard drivers,v2022.10,$(CONFIG_KEYBOARD))
 	@# 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.

doc/develop/driver-model/migration.rst

@@ -98,3 +98,11 @@ Deadline: 2021.10
 The I2C subsystem has supported the driver model since early 2015.
 Maintainers should submit patches switching over to using CONFIG_DM_I2C and
 other base driver model options in time for inclusion in the 2021.10 release.
+
+CONFIG_KEYBOARD
+---------------
+Deadline: 2022.10
+
+This is a legacy option which has been replaced by driver model.
+Maintainers should submit patches switching over to using CONFIG_DM_KEYBOARD and
+other base driver model options in time for inclusion in the 2022.10 release.