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/usb/gadget/epautoconf.c b/drivers/usb/gadget/epautoconf.c
index 7da334f..01337d6 100644
--- a/drivers/usb/gadget/epautoconf.c
+++ b/drivers/usb/gadget/epautoconf.c
@@ -144,7 +144,7 @@
 
 	/* report address */
 	if (isdigit(ep->name[2])) {
-		u8	num = simple_strtoul(&ep->name[2], NULL, 10);
+		u8	num = dectoul(&ep->name[2], NULL);
 		desc->bEndpointAddress |= num;
 #ifdef	MANY_ENDPOINTS
 	} else if (desc->bEndpointAddress & USB_DIR_IN) {
diff --git a/drivers/usb/gadget/ether.c b/drivers/usb/gadget/ether.c
index 16922ff..4307328 100644
--- a/drivers/usb/gadget/ether.c
+++ b/drivers/usb/gadget/ether.c
@@ -2401,8 +2401,7 @@
 	usb_gadget_connect(gadget);
 
 	if (env_get("cdc_connect_timeout"))
-		timeout = simple_strtoul(env_get("cdc_connect_timeout"),
-						NULL, 10) * CONFIG_SYS_HZ;
+		timeout = dectoul(env_get("cdc_connect_timeout"), NULL) * CONFIG_SYS_HZ;
 	ts = get_timer(0);
 	while (!dev->network_started) {
 		/* Handle control-c and timeouts */