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/qe/dm_qe_uec.c b/drivers/net/qe/dm_qe_uec.c
index eb0501b..a12c8cd 100644
--- a/drivers/net/qe/dm_qe_uec.c
+++ b/drivers/net/qe/dm_qe_uec.c
@@ -938,7 +938,7 @@
 		return QE_CLK_NONE;
 
 	if (strncasecmp(source, "brg", 3) == 0) {
-		i = simple_strtoul(source + 3, NULL, 10);
+		i = dectoul(source + 3, NULL);
 		if (i >= 1 && i <= 16)
 			return (QE_BRG1 - 1) + i;
 		else
@@ -946,7 +946,7 @@
 	}
 
 	if (strncasecmp(source, "clk", 3) == 0) {
-		i = simple_strtoul(source + 3, NULL, 10);
+		i = dectoul(source + 3, NULL);
 		if (i >= 1 && i <= 24)
 			return (QE_CLK1 - 1) + i;
 		else