clocksource/drivers/timer-ti-dm: Make timer selectable for ARCH_K3

clocksource/drivers/timer-ti-dm: Make timer selectable for ARCH_K3

Let's make timer-ti-dm selectable for ARCH_K3, and add a separate option
for OMAP_DM_SYSTIMER as there should be no need for it on ARCH_K3.

For older TI SoCs, we are already selecting OMAP_DM_TIMER in
arch/arm/mach-omap*/Kconfig. For mach-omap2, we need to now also select
OMAP_DM_SYSTIMER.

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/20220408101715.43697-3-tony@atomide.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>