clocksource/drivers/arm_arch_timer: Use kstrtobool() instead of strtobool()

strtobool() is the same as kstrtobool().
However, the latter is more used within the kernel.

In order to remove strtobool() and slightly simplify kstrtox.h, switch to
the other function name.

While at it, include the corresponding header file (<linux/kstrtox.h>)
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/f430bb12e12eb225ab1206db0be64b755ddafbdc.1667336095.git.christophe.jaillet@wanadoo.frSigned-off-by: Daniel Lezcano <daniel.lezcano@kernel.org>

drivers/clocksource/arm_arch_timer.c

@@ -18,6 +18,7 @@
 #include <linux/clocksource.h>
 #include <linux/clocksource_ids.h>
 #include <linux/interrupt.h>
+#include <linux/kstrtox.h>
 #include <linux/of_irq.h>
 #include <linux/of_address.h>
 #include <linux/io.h>
@@ -97,7 +98,7 @@ static bool evtstrm_enable __ro_after_init = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EV
 
 static int __init early_evtstrm_cfg(char *buf)
 {
-	return strtobool(buf, &evtstrm_enable);
+	return kstrtobool(buf, &evtstrm_enable);
 }
 early_param("clocksource.arm_arch_timer.evtstrm", early_evtstrm_cfg);