clocksource/drivers/timer-ti-dm: Make driver selection bool for TI K3

The clocksource drivers do not currently have loadable modules as
pointed out by Daniel Lezcano <daniel.lezcano@linaro.org>.

Let's reconsider this later on once timer removal discussion has been
done, and set timer-ti-dm to bool for TI K3 SoC.

Cc: Keerthy <j-keerthy@ti.com>
Cc: Nishanth Menon <nm@ti.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20220523151448.23732-1-tony@atomide.comSigned-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/Kconfig

@@ -57,7 +57,8 @@ config DIGICOLOR_TIMER
 	  Enables the support for the digicolor timer driver.
 
 config OMAP_DM_TIMER
-	tristate "OMAP dual-mode timer driver" if ARCH_K3 || COMPILE_TEST
+	bool "OMAP dual-mode timer driver" if ARCH_K3 || COMPILE_TEST
+	default y if ARCH_K3
 	select TIMER_OF
 	help
 	  Enables the support for the TI dual-mode timer driver.