global: Convert simple_strtoul() with decimal to dectoul()

It is a pain to have to specify the value 10 in each call. Add a new
dectoul() function and update the code to use it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 131099c..8c77777 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/drivers/gpio/gpio-uclass.c
@@ -122,7 +122,7 @@
 	int numeric;
 	int ret;
 
-	numeric = isdigit(*name) ? simple_strtoul(name, NULL, 10) : -1;
+	numeric = isdigit(*name) ? dectoul(name, NULL) : -1;
 	for (ret = uclass_first_device(UCLASS_GPIO, &dev);
 	     dev;
 	     ret = uclass_next_device(&dev)) {
diff --git a/drivers/gpio/mxs_gpio.c b/drivers/gpio/mxs_gpio.c
index 5775a22..7b9d88a 100644
--- a/drivers/gpio/mxs_gpio.c
+++ b/drivers/gpio/mxs_gpio.c
@@ -123,12 +123,12 @@
 	unsigned bank, pin;
 	char *end;
 
-	bank = simple_strtoul(name, &end, 10);
+	bank = dectoul(name, &end);
 
 	if (!*end || *end != ':')
 		return bank;
 
-	pin = simple_strtoul(end + 1, NULL, 10);
+	pin = dectoul(end + 1, NULL);
 
 	return (bank << MXS_PAD_BANK_SHIFT) | (pin << MXS_PAD_PIN_SHIFT);
 }
diff --git a/drivers/gpio/tca642x.c b/drivers/gpio/tca642x.c
index 7007c7a..7f67f96 100644
--- a/drivers/gpio/tca642x.c
+++ b/drivers/gpio/tca642x.c
@@ -262,11 +262,11 @@
 
 	/* arg2 used as chip number or pin number */
 	if (argc > 2)
-		ul_arg2 = simple_strtoul(argv[2], NULL, 10);
+		ul_arg2 = dectoul(argv[2], NULL);
 
 	/* arg3 used as pin or invert value */
 	if (argc > 3)
-		ul_arg3 = simple_strtoul(argv[3], NULL, 10) & 0x1;
+		ul_arg3 = dectoul(argv[3], NULL) & 0x1;
 
 	switch ((int)c->cmd) {
 	case TCA642X_CMD_INFO: