clocksource/drivers/exynos_mct: Explicitly return 0 for shared timer

For a shared timers, the mct_init_dt() should not initialize the clock
even with global comparator. This is not an error, thus the function
should simply return 0, not 'ret'.

This also fixes smatch warning:

drivers/clocksource/exynos_mct.c:635 mct_init_dt() warn: missing error code? 'ret'

Reported-by: kernel test robot <[e-mail]>
Reported-by: Dan Carpenter <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]/
Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Vincent Whitchurch <[e-mail]>
Reviewed-by: Alim Akhtar <[e-mail]>
Signed-off-by: Daniel Lezcano <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/clocksource/exynos_mct.c

···
 	 * processor cannot use the global comparator.
 	 */
 	if (frc_shared)
-		return ret;
+		return 0;
 
 	return exynos4_clockevent_init();
 }