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/net/netconsole.c b/drivers/net/netconsole.c
index f1d0630..cec96c5 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -87,7 +87,7 @@
 				return -1;	/* ncip is 0.0.0.0 */
 			p = strchr(env_get("ncip"), ':');
 			if (p != NULL) {
-				nc_out_port = simple_strtoul(p + 1, NULL, 10);
+				nc_out_port = dectoul(p + 1, NULL);
 				nc_in_port = nc_out_port;
 			}
 		} else {
@@ -96,10 +96,10 @@
 
 		p = env_get("ncoutport");
 		if (p != NULL)
-			nc_out_port = simple_strtoul(p, NULL, 10);
+			nc_out_port = dectoul(p, NULL);
 		p = env_get("ncinport");
 		if (p != NULL)
-			nc_in_port = simple_strtoul(p, NULL, 10);
+			nc_in_port = dectoul(p, NULL);
 
 		if (is_broadcast(nc_ip))
 			/* broadcast MAC address */