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>

cmd/sata.c

@@ -88,7 +88,7 @@ static int do_sata(struct cmd_tbl *cmdtp, int flag, int argc,
 		int devnum = 0;
 
 		if (argc == 3)
-			devnum = (int)simple_strtoul(argv[2], NULL, 10);
+			devnum = (int)dectoul(argv[2], NULL);
 		if (!strcmp(argv[1], "stop"))
 			return sata_remove(devnum);