clocksource/drivers/riscv: Get rid of clocksource_arch_init() callback

Having a clocksource_arch_init() callback always sets vdso_clock_mode to
VDSO_CLOCKMODE_ARCHTIMER if GENERIC_GETTIMEOFDAY is enabled, this is
required for the riscv-timer.

This works for platforms where just riscv-timer clocksource is present.
On platforms where other clock sources are available we want them to
register with vdso_clock_mode set to VDSO_CLOCKMODE_NONE.

On the Renesas RZ/Five SoC OSTM block can be used as clocksource [0], to
avoid multiple clock sources being registered as VDSO_CLOCKMODE_ARCHTIMER
move setting of vdso_clock_mode in the riscv-timer driver instead of doing
this in clocksource_arch_init() callback as done similarly for ARM/64
architecture.

[0] drivers/clocksource/renesas-ostm.c

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Tested-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20221229224601.103851-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

arch/riscv/Kconfig

@@ -12,7 +12,6 @@ config 32BIT
 
 config RISCV
 	def_bool y
-	select ARCH_CLOCKSOURCE_INIT
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_HAS_BINFMT_FLAT

arch/riscv/kernel/time.c

@@ -33,12 +33,3 @@ void __init time_init(void)
 
 	tick_setup_hrtimer_broadcast();
 }
-
-void clocksource_arch_init(struct clocksource *cs)
-{
-#ifdef CONFIG_GENERIC_GETTIMEOFDAY
-	cs->vdso_clock_mode = VDSO_CLOCKMODE_ARCHTIMER;
-#else
-	cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE;
-#endif
-}

drivers/clocksource/timer-riscv.c

@@ -78,6 +78,11 @@ static struct clocksource riscv_clocksource = {
 	.mask		= CLOCKSOURCE_MASK(64),
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 	.read		= riscv_clocksource_rdtime,
+#if IS_ENABLED(CONFIG_GENERIC_GETTIMEOFDAY)
+	.vdso_clock_mode = VDSO_CLOCKMODE_ARCHTIMER,
+#else
+	.vdso_clock_mode = VDSO_CLOCKMODE_NONE,
+#endif
 };
 
 static int riscv_timer_starting_cpu(unsigned int cpu)