gpio: aggregator: Replace custom get_arg() with a generic next_arg()

cmdline library provides next_arg() helper to traverse over parameters
and their values given in command line. Replace custom approach in the driver
by it.

Signed-off-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>

drivers/gpio/gpio-aggregator.c

···
 static DEFINE_MUTEX(gpio_aggregator_lock);	/* protects idr */
 static DEFINE_IDR(gpio_aggregator_idr);
 
-static char *get_arg(char **args)
-{
-	char *start, *end;
-
-	start = skip_spaces(*args);
-	if (!*start)
-		return NULL;
-
-	if (*start == '"') {
-		/* Quoted arg */
-		end = strchr(++start, '"');
-		if (!end)
-			return ERR_PTR(-EINVAL);
-	} else {
-		/* Unquoted arg */
-		for (end = start; *end && !isspace(*end); end++) ;
-	}
-
-	if (*end)
-		*end++ = '\0';
-
-	*args = end;
-	return start;
-}
-
 static int aggr_add_gpio(struct gpio_aggregator *aggr, const char *key,
 			 int hwnum, unsigned int *n)
 {
···
 
 static int aggr_parse(struct gpio_aggregator *aggr)
 {
+	char *args = skip_spaces(aggr->args);
 	char *name, *offsets, *p;
-	char *args = aggr->args;
 	unsigned long *bitmap;
 	unsigned int i, n = 0;
 	int error = 0;
···
 	if (!bitmap)
 		return -ENOMEM;
 
-	for (name = get_arg(&args), offsets = get_arg(&args); name;
-	     offsets = get_arg(&args)) {
-		if (IS_ERR(name)) {
-			pr_err("Cannot get GPIO specifier: %pe\n", name);
-			error = PTR_ERR(name);
-			goto free_bitmap;
-		}
+	args = next_arg(args, &name, &p);
+	while (*args) {
+		args = next_arg(args, &offsets, &p);
 
 		p = get_options(offsets, 0, &error);
 		if (error == 0 || *p) {
···
 				goto free_bitmap;
 		}
 
-		name = get_arg(&args);
+		args = next_arg(args, &name, &p);
 	}
 
 	if (!n) {