init: Replace simple_strtoul() with kstrtouint() in root_delay_setup()

Replace deprecated simple_strtoul() with kstrtouint() for better error
handling and input validation. Return 0 on parsing failure to indicate
invalid parameter, maintaining existing behavior for valid inputs.

The simple_strtoul() function is deprecated in favor of kstrtoint()
family functions which provide better error handling and are recommended
for new code and replacements.

Signed-off-by: Kaushlendra Kumar <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Reviewed-by: Jan Kara <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

init/do_mounts.c

···
 static unsigned int __initdata root_delay;
 static int __init root_delay_setup(char *str)
 {
-	root_delay = simple_strtoul(str, NULL, 0);
+	if (kstrtouint(str, 0, &root_delay))
+		return 0;
 	return 1;
 }