mm/page_table_check.c: use strtobool for param parsing

Use strtobool rather than open coding "on" and "off" parsing.

Link: https://lkml.kernel.org/r/20220227181038.126926-1-linux@treblig.orgSigned-off-by: NDr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/page_table_check.c

@@ -23,15 +23,7 @@ EXPORT_SYMBOL(page_table_check_disabled);
 
 static int __init early_page_table_check_param(char *buf)
 {
-	if (!buf)
-		return -EINVAL;
-
-	if (strcmp(buf, "on") == 0)
-		__page_table_check_enabled = true;
-	else if (strcmp(buf, "off") == 0)
-		__page_table_check_enabled = false;
-
-	return 0;
+	return strtobool(buf, &__page_table_check_enabled);
 }
 
 early_param("page_table_check", early_page_table_check_param);